Customizing the look of your PC/Avatar is an important part of the appeal, so much so that I consider it a core part of the gameplay in roleplaying games of this sort. it contributes significantly to the "play" part of the gameplay.
This isn't an MMO where we have limited character slots per server, and they need to gatekeep appearance in order to push haircut microsales or whatever. I think its much more important here that an appearance change just be convenient and fun, and not like a frustrating or punishing time sink.
I would prefer it just being built into the Character Sheet tab, but that said, I don't really care if they want to make it more a part of the world building, or incorporate some sort of minor cost in gold to see a stylist at camp or whatnot, as long as its relatively simple for the player to access.
It's also worth noting that the lighting conditions in the Nautiloid prologue are very different from the lighting conditions on the Beach (which is closer to the previews shown in the character creation menu), so I can imagine many players thinking something looks great or looks horrible based on something like lighting, only to discover later they are now unhappy with that choice, but can't do anything to tweak it short of rolling another toon.
Since they already ditched the custom D&D portrait as a worthwhile concept, and have gone with 3D model presets for everything now, it's even more important for a game like BG3 to be as flexible as it can in this regard.
