Well, I think that a lot of the people who react poorly to concrit and yet admit there are problems with their writing is because concrit reminds them of their failures and they react negatively to it. Is it immature? Of course. But I have to say, it's pretty damn hard to swallow your pride and take concrit when all you want to do is yell "I know! I know it's horrible! Don't rub it in!". LOL. It takes so much maturity and conscious effort I can't find it in me to condemn people who fail to do it.