I think that'd be a great addition, considering there are already cheat mods and the such available, so if people wanted to unbalance their game it's up to the player to choose to do so, and there's no reason for people to not be able to play as they'd like. The only thing I could consider is that there could be story related issues with bringing in a hero character at a random point in the game, but if that's not a major issue it could just be made to where said new player would just have to make a custom character rather than picking one of the heroes.