Just heard about this and i looked it up on reddit. Saw a big post from a Korean player who are 3 months ahead of global and he highlighted numerous cases over and over again where the company NERFED characters after players purchased them. Not just once but numerous occasions and VERY significant nerfs.
While i can appreciate game balance, no way in fuck would i play a game that nerfed characters after i spent potentially ALOT of $$$ to aquire them without any form of refund/accomondation. Lets be honest these games are simple as fuck compared to many games and make a fuck ton of money, if you can't balance ahead of time dont release the characters that fast.
Would never spend a penny on a company that did this as common practice. I play DFFOO since close to release and i do not recall one single nerf to date of even the lighest. They actually go in and buff characters that are viewed as non-meta and lost due to power creep (granted that helps them generate more interest and $$$) but much better then nerfing approach.