I haven't barred people from playing them, but I did remove halflings, dwarves and gnomes from my world since I find all of them really boring. (Sorry. To me they're just short human, short wide human, and short wacky human.) It's not that I think they're bad, it's just that I don't care about them, so I didn't want to make a default place for them. I'd still let somebody play one if they wanted, but it would be up to the player to tell me what they are and where it would fit.
Half-orcs and half-elves are a hard no though; they're just elves and orcs, lest we endorse the idea that some races are "true" races and others are "mixed" and all the creepy weird racism bound up in that. In my world almost every living humanoid can interbreed, so rather than make a big list of hybrid "races" the policy is that you pick the mechanical package that represents your character best, and I don't care which of your parents had pointy ears.
As for who I made wildly different, my kobolds have almost no dragon in them and aren't very humanoid; they're made of equal parts dog and lizard, on a very ferrety body. Culturally they have a lot of proud warrior stuff going on, but they also come up a lot as weirdo inventor types, since tunneling extensively underground means they're the people who most often find the pre-apocalypse magitech relics.
Also my goblins are round and hairy, with a pronounced underbite, comically short limbs, big frantic eyes and sort of batty ears right at the tops of their heads. They're misunderstood rather than evil; mostly they're just trash-eating communists who don't see an issue with taking what's not being used. Kind of D&D wombles.
Oh right, and the eladrin aren't really of fey origin, they just did a massive ritual one time trying to steal immortality from the feywild. It didn't exactly work, but it did let them come back millennia later and colonise the elves under the pretence of being "cousins".