It's not really about that. Console games have a sort of hard cap in place for how much a developer can require someone to download post-launch cumulatively. Anything a player has to download, regardless of whether or not they want it, counts toward that limit. Usually, it's just Title Updates, but with the scenario you're describing, it's characters, which could easily break the limit. For the Xbox 360, it's 256MB. I don't know how high it is for the PS3, but I'd be willing to bet it's also around there.