I may be remembering the things differently, but I think the reason Hasbro stepped in was because the MLP game was geting so much attention (being that it was presented at EVO or something like that), and so, now that there was no Pony fighting game, they decided to make another game with the same concept, and THAT'S WHEN they started to ask for money.

But it's been so many years, so I'm not really sure about that.