You can argue that yes, going shirtless in the middle of the desert is a bad idea. But Ul'dah itself is probably not oppressively hot and there seems to be plenty of water, given how a bunch can be spared on a fountain in the Gold Court. Most of Ul'dah seems to have plenty of shade already if not indoors. So, really, there's no reason people can't go shirtless if they want to.
Personally, I feel policing people's attire in general is dumb when the elements aren't overwhelmingly a factor. Wearing a bikini in Coerthas is a breach of immersion. Something like this is decidedly more subjective.
Personally, I feel policing people's attire in general is dumb when the elements aren't overwhelmingly a factor. Wearing a bikini in Coerthas is a breach of immersion. Something like this is decidedly more subjective.