Hmm....
I believe for a realistic group to deny a winged character is acceptable and perfectly logical.
But think before you call a semi-realistic group stupid or rude when they deny your winged characters. They are called semi-realistic because they mostly allow unrealistic colors and maybe some traits but still want to keep a level of realism in their roleplays, hence why the 'realistic' word in this particular group. In many cases wings are already too unrealistic for a semi-realistic group. Hence why they deny winged characters most of the time.
Actually, I wouldnt be angry for fantasy RPs denying winged characters. After all... it depends on the roleplay content. Many are afraid that a winged character would abuse their ability to fly when doing certain actions or in fighting situations, attacking from the air while making the other appear stupid. I had bad experience before with people like that. Hence why most Rps where fighting between characters cannot be avoided, they make sure to not accept winged characters for this reason.
But I do agree that there should be more winged roleplay groups. I am attempting to find one for my dragon that I recently made but so far had no luck.