My thoughts as well. I won't tell you you can't play Bugs Bunny, I will tell you that I've thought about what races I allow and how they fit into my campaign world. I know where they live, what their relationships are with their neighbors, I've put a bit of spin here and there on their cultures. These are the races you are allowed to play, how can we make that work for you?
There are many different types of games. If I'm playing a video game sometimes I'm going to play a Borderlands game with overtly silly NPCs, story and over-the-top styling and game play. Other times I'm going to play a Witcher game with it's more grounded fantasy feel.
It's the same with D&D campaign. Yes, I could add an anthropomorphic hippo to my game. No, I'm not going to because I've already decided what races I allow, I was quite up front about it when I discussed my game. In part it's become a bit of a screening device over the years. If you can't compromise and play one of the half dozen races I do allow, I'm probably not running the game you want. I used to allow anything and everything and it was a bit of a disaster at times. I finally learned to say no when a player wanted to have a half dragon half vampire PC.
You can't please everyone and if you try you frequently end up pleasing no one. If someone wants to join my game and insists that they must play a drow (and have all the benefits and not the sunlight penalty, of course) I probably don't want them in my game in the first place.
