That is the real question. As far as I know noboby knows. The best thing I can think of is the theory that we are living in a black hole. If we are living in an irregularity then many things in it would be irregular.
Another good theroy is that the reason for the Big Bang is the uneven balance in the contents of the `early universe`. So maybe the Big Bang was a cosmic irregularitiy.
I`m sure that there are several others but I just can`t remember them.
Each way you can always think cosmic irregularities down to this: If all those things are irregularities, then what is to say the life isn`t an irregularity?