I for one didn't find the last Hulk movie to be that good. I didn't even get psyched up for it when it came out. I would of rather watched the TV series...it was good haha.
But anyway movies are being remade because either new technology is available to make the special fx much better (outdated/old) or the first just plain didn't live up to what most people wanted. That's my take on it though.
The more superhero movies the merrier IMO.