SF4 felt like what were called the Dream Match versions of KoF, where they ignored the story stuff in favor of being able to jam all the characters into one game, whether they were alive or dead or whatever in the story. SF4 was a big return to form for Street Fighter, it was full of all the fan favorite characters in the style people remembered them in, the entire cast of SF2, characters from Alpha and Third Strike not looking any different even though those two series are pretty far apart in the time line. Story wasn't very important at all. And I think that's fine, people like the characters and people liked playing them all in SF4, especially since it'd been so long since we'd seen them all in a game together like that.
But you can't really do that again immediately, so it seems like SF5 is shifting back into caring about the story a little more, aging characters, moving stories forward etc. I think its fun to have both types of approaches. KoF used to do a trilogy of story-focused games, then a dream match, then another trilogy, then a dream match.