Who are you to judge that? You're the DM! By allowing you to DM, your players cede you the authority to judge all sorts of things. You just have to pick the right battles to fight so that your players continue to be satisfied, make the compromises you need to make, and enforce the restrictions you need to enforce for the good of the game.
Over in another thread on whether or not classes need to be balanced, a couple of posters are relating "horror" stories of PC that, through their players' build choices, were one dimensional and ineffective outside of that dimension. Well, that partly stems from the attitude above - who are you to judge? You're the guy who's supposed to be helping the game work. You're the one who should be telling PCs that a concept won't work, that they need to pick up some better offense for their own good, that they need to work together with their fellow players. This is of critical importance with any game system highly responsive to player choices from point-buy systems like Champions and Mutants and Masterminds to class-based systems that nevertheless have lots of options like D&D.
It may well be that playing a leopard man won't have a whole lot of impact on mechanical balance nor on social interactions. In that case, it's OK to bend as DM even if you don't particularly like leopard men or think they're kind of silly. But if the player wants to stack up a paladin/monk/<whatever else gives out ridiculous save bonuses> to utterly redline his saves but leave his offense about the level of a toddler with a wet noodle, it's probably time to step up and judge and tell him to cut it out.