I'm pretty sure there's a hefty list of still-legal characters that "cheat" just as much - if not more - than Chun-li does -.-' Chun-li can play one form on your turn. We also have Akuma who can make you fail something every turn of the game, (as well as commit your whole staging area) Alex with his 9-10HS/28VIT, Sakura who tutors from her discard every turn, Ibuki who can auto-pass almost anything - the list goes on.
Chun-li is no more "broken" than any of these other high-powered characters, she just happens to be the newest one. Just get used to seeing her the same way you've gotten used to seeing the rest of the bunch.
*Plus, we're all talking about a "Block three" that isn't complete (or intended to be played at all) yet. There could be any number of things (i.e. a new TYPFG/Roam the World) upcoming in set 12 that would help combat her.