"Chainmail bikini" Yay buzzwords. Its neither chainmail not a bikini such its not a chainmail bikini and even if it was a chainmail bikini if thats the aesthetic vision of Larian then its good.
It's not about the literal chainmail bikini and this is not simply a buzzword. Just because the trope name uses the word bikini, it also doesn't mean it's all about sexism -- the chainmail bikini is a defined trope.
Look at the illustration on the trope page. It's a pretty good representation of the areas that are visually protected when an elf puts on armour in D:OS2.
The problem is that it's impractical and immersion breaking. If you're going to go to the effort of wearing armour, you'll probably want to try protecting your midriff. I don't know why it's so important for the elves to always try so hard at being sexy.
