I don't understand how making the game broken makes more money.

Unbalanced game = less people play = less money.

Sure you can pull the #LCSBIGPLAYS claim, and in some ways that's true . But if riot were willing to make the game completely broken and unfun (not saying that it is right now, but that's just my opinion) just so that they can have more lcs diversity (and generally this doesn't cause lcs diversity, it just changes the champions that people want to play, but this is just as an example.) then they would have implemented 10 bans years ago.