Post launch character being earnable for free through game play means that there's probably going to be a grind component to the game (ie. in-game currency) sort of like LoL.
Although you do need a ceratin number of games played to earn a new character in league, I've never viewed it that bad since like dota or sf or CS or TF2, if it's a game you just love playing, you should be able to earn the new content rather quickly. Especially if you hold sessions and just bring your system.
It was a pain in arcade MVC2, but with dreamcast MVC2 (outside of leaving it on training overnight) you just get the characters you use and it's not a problem.
I love that they are doing this, such a great thing, now people won't complain how much a character costs when you can just play some street fighter and get them!.