I never used to wear pocket squares. Then I started hanging out around here. I know have gobs of them and won't wear a jacket without one. I look at it as a way of accenting an outfit or finishing it off. When I don't/can't/shouldn't wear a tie it gives me another element to make an outfit more 'me'.
Besides, it's just plain 'right', and someone has to stand for what's right.
If you're not going to wear one, commission your suits without a pocket on the breast then!