For me personally, another reason I play stick now is that I don't want to make excuses. The biggest complaint in our arcades was that there was no controller port. When I started off as a d-pad player I just couldn't do what I wanted to and that really pissed me off. I took it upon myself to learn stick so that I'd know I played to the best of my abilities. Imagine going to a tournament and they only offer one of the choices and it's the one you can't use. Lost opportunity right there. It paid off when I went to the Philippines and I was totally comfortable playing with the BR machines. I also joined the Gamestop midnight release tournament and it was stick only. My friend and I joined and he was better than me but he plays d-pad and he didn't even get far. I however, did what I could and managed to get 3rd place. He's very disappointed but I was content at what I did.
Stick doesn't give you thumb blisters. When I started, my wrist and forearm hurt for a while because I was pretty stiff with the inputs but after a while I got used to it and I flowed a little better.