I agree wholeheartedly!
I feel like the lack of this feature is what's keeping me from really getting into this game (which is silly, I know, but every player is different). Just google "bg3 wave mothers robe" to see some of the more ridiculous looks that you can end up with for your characters if you simply want to use a good wizard robe that you picked up. The result overshoots immersion-breaking so much that it goes all the way to the moon and back. Also, as a monk or barbarian, there really aren't any good-looking clothing options in the game at all so allowing us to use our starting gear as cosmetic clothing would be nice.
Playing Dnd is all about having your character and being immersed in it and the world so allowing us to customize the looks and clothing for that character more without sacrificing the thrill of finding new gear is really important! So it's clear that this should be something that you should focus on for the next patch, now that we have the magic mirror.
Apart from transmog, I would also love some more capes and clothing options, thanks!

Here's some additional reading on the topic:
https://www.gamesradar.com/all-bald...n-be-stylish-without-compromising-stats/https://www.pcgamesn.com/baldurs-gate-3/transmog-mod