Certainly anyone is welcome to any dismal belief of their choosing, but I'll argue why general pessimism is just un-pragmatic, and therefore should be kept at a minimum as much as possible.
***Ironically, while atheism may enstill a sort of freedom from certain "laws" of a religion, it certainly does act as a prison as well. You see, its not that atheists don't want a god or don't want to go to heaven and have eternal life. Trust me, eternal life sounds wonderful! However, when I think of the concept, I feel that I would only be kidding myself. So not believing in god sets a couple of restraints on life as an atheist.***
All pessimistic beliefs offer both freedom and imprisonment (maybe that's even true of all beliefs?). The freedom of pessimism comes from not having to defend, hold onto hope, being patient, etc for a positive solution. For example, if I hold the pessimistic belief that the world will sooner or later be enveloped in nuclear war, then I don't have to worry about wars and war drums, etc. I already know that humanity will destroy itself, perhaps very soon, so I have already accepted that fact and talk about war, etc is inevitable and I am 'free' to accept life as it is right now. I can enjoy this moment without putting false hope in who we elect, or what is done about global warming, etc. I might even gain a 'higher perspective' and start looking differently at cochroaches, bacteria, and other lifeforms which will survive just fine any global catastrophe. The imprisonment comes in that it is very sad to know (i.e., think that I know) that humanity will soon perish and all the bad news that this creates.
***1) No afterlife. You know, it is widely mistaken that atheists have no love for life. This is insanity! With nothing more than the life we have now, it is more precious to us, than I think theists can appreciate. No afterlife means that if we make one mistake, our life could be over. Death could come tomorrow, live today. This doesn't mean "Anything Goes", but it is a philosophy of life that really means, don't wait or hold back on experience. Don't hold back on education waiting for tomorrow. Don't hold back, not going to that place in the world. Don't hold back, from moving where you want because of your family or even worse, because you are afraid of change. To do otherwise would be a waste of life, a life that atheists realize is finite, and not everlasting.***
Similarly like all pessimistic beliefs, life is usually okay *now*, but it is usually in the future which is where they have pessimism. Therefore, the *now* becomes all important and this often leads to a change in lifestyle. Many pessimists do things that they normally wouldn't do before. Since most of society around them is not so pessimistic, the behavior of the pessimistic people is often slightly different (either 'positively' or 'negatively'). This is not always the case since different people act differently to pessimistic news. For example, when I first heard about 9/11 it originally confirmed what my pessimistic view on terrorism had deep down expected would happen (but, in a much less intense way since I had far more ominous expectations of a terrorist threat). However, all of that didn't change me. Some people, I understand, fell into depression and some are still in depression to this day. Some people became very angry, etc. I'm not saying that I didn't experience some rather disturbing emotions, it was just that they didn't affect my behavior as far as I know.
***2) No set in stone moral structure. Not "no morals" as Christians like to harmp. I've looked all around faiths, from buddhism to taoism to judiaism. With no stone morality structure, one is allowed to adjust. What does Rush say in a song, "Culture is the curse to the thinking class". Culture hurts civilizations. Its good to a point, but it certainly acts as an anchor. Like today, Americans are so full of their culture that they can't possibly understand life in Iraq or Saudi Arabia or Afghanistan. This lack of ability to understand other people is what holds society back as a whole. Atheism allows a bridge to any idea or cultural custom. Take the best, leave the rest.***
Pessimism, in general, can result in positive outcomes. For example, if you are pessimistic and think all out nuclear war is very soon to occur (within our lifetime), then you might find common connection with all people. You might be less concerned about cultural differences and focus on the fact that we are all human and that our species will soon be exterminated from the globe. I'm sure there are numerous of moral benefits that can come about. Of course, this must be balanced against the negative morality that develops where, if everyone believes in this kind of pessimistism as inevitable, we could expect major changes to society (e.g., decrease in child births among the more responsible, lack of investment in new construction, etc).
***When I think of god, I think of a book written by men, whether they be Sumerians or Bedouins. When I read most books, I see arbitrariness. When I read the Tao te Ching, I read universality. Wisdom is written in terms that favor no person. So many people believe they follow the right god. So many, that I feel none of them are right.***
Once you lock onto a pessimistic view like global destruction, it really doesn't matter which economic views are best (capitalism, socialism, or communism), or which kind of government is best (democracy, dictatorship, theocracy, monarchy, etc), or even which kind of social programs are best (education, individual freedoms, etc). To such a kind of pessimist, the world is totally off-base in pursuing a continuing civilization since none of it is going to last.
Likewise, an atheist looks at religion and humanity's attempt to understand God and find meaning in those attempts, and this becomes only evidence that God either doesn't exist or it wouldn't matter even if he did since obviously we are just guessing about his existence and he doesn't seem to care in any case (i.e., assuming he even existed). This, in my view, is just an extension of a pessimistic view where human attempts are seen in a pessimistic light.
***Why does atheism exist? Well mostly in part to education. Atheism is growing, al beit, slowly. As people are allowed to think for themselves, they grow away from the necessity of god. God is a crutch. It is a necessary crutch, a "necessary evil" as Freud puts it. But not for all people. Atheism exists, because I think it is a logical answer to an illogical question, "Why are we here?" Atheism answers, "Well, we are. Might as well make the best of it. Pass the Cheez-Its."***
Notice how well your paragraph fits in with any pessimistic paradigm:
Why does [general pessimism about human survival] exist? Well mostly in part to education. [General pessimism about human survival] is growing, al beit, slowly. As people are allowed to think for themselves, they grow away from the necessity of [optimism about human survival]. [Optimism about human survival] is a crutch. It is a necessary crutch, a "necessary evil" as Freud puts it. But not for all people. [General pessimism about human surival] exists, because I think it is a logical answer to an illogical question, ["Will we always be here?"] [The pessimist about human surival] answers, "Well, we are [right now]. Might as well make the best of it. Pass the Cheez-Its. :^)
Fits in pretty well, doesn't it? Well, my reply to pessimism in general is that the discussion of pessimism does provide a positive purpose since we cannot keep our heads buried in the sand about whatever pessimists claim to be true. Pessimism is in response to fear, and that fear is often legitimate. If we want to be optimistic, then we must continue to adequately answer the pessimistic challenge. This doesn't mean that we give in to pessimistic thinking (e.g., atheism, agnosticism), rather we learn from the pessimist and re-direct our efforts (e.g., to longterm human survival, combating of terrorism, or combating of atheist or agnostic notions, etc). However, what really separates the optimist from the pessimist is not policies or who has the best argument, what separates the optimist and pessimist is ideology. This ideology is something that one must choose. You must choose to be an optimist or you choose to be a pessimist. If you choose to be an optimist, you risk being wrong. You might look with disbelief at the events of something like 9/11 (or much worse a nuclear explosion or series of them on major world cities), but going through life as a pessimist (no matter how reasonable your view) is no way to go through life. It's understandable to be a pessimist if the pessimist view is the only reasonable view, but if there is even one optimist view that is reasonable, far better to see the cup as half full rather than half empty.
Warm regards, Harv