Because when FF7 came out he was considered to be new and interesting. For better or worse, Cloud set the template for characters of that type.
When I had FF7, I absolutely loved it. Not to sound like a fanboy, but I don't think it's fair to judge the game using today's standards, as a hell of lot has changed since 1997. No, it hasn't aged the best, but in my humble opinion, not many RPGs were on the level FF7 was when it debuted. It didn't sell 10 million copies for nothing.
That argument falls apart when you realize that today's standards haven't really even changed. I am perfectly fine with judging a particular game from 1997 by today's standards. But I would only do it with this specific game though,
because that game is the primary reason our "standards" haven't changed in over 10 years. You don't even need proof to know this is true, because who here can honestly argue that if they actually did re-make FF7 today it wouldn't sell even more than 10 million copies in pre-release purchases alone?
You can't deny that people like this shit. All the more reason more people should be viewing with a critical eye what so many pass off as simply "something they enjoy playing". They may not need a reason to think that, but that doesn't stop me from viewing it as a sickeningly curious phenomena that simply begs for an explanation beyond "Everything about this game is shitty, which must be why some people still like it more than anything else."