I use to wear a leather Cardillo belt, it was a great belt and i used it when squatting heavy or doing anything heavy for that matter. I believe it helped a whole lot! I just think its a bad idea when you see guys wearing the belt throughout their entire workout, and wearing it for shit you dont need to wear a belt for.
I am pretty sure when its over used that it weakens your back and abdominal muscle, and you become dependant on the belt which is not good especialy when u decidee to not wear it or forget to bring it the gym and you then try doing same shit u did with the belt and this is when injury occur!
So I am an advocate of wearing a belt when lifting heavy! But oppose wearing a belt for every little exercise you do, thats no good!