Zardnaar
Legend
I'm not sure "I don't like that race" or "I don't like that class" are exactly frivolous reasons. Banning a player's favorite race because it's that player's favorite race is emphatically an asshat maneuver.
I'm willing to, but I'm at least as likely to play a human as not, and I'm more comfortable figuring out characters I can understand and relate to than ones I cannot. OTOH, I don't care what other people play when I'm playing (though I ban some races as a GM).
There is a difference between "because I don't like it" and "because I can." One is capricious, the other is not.
I wouldn't ban it because it's their favorite race I already have made the decision as to what's available in advance.
If it is a players favorite race tough luck.