Why can't we look up to 90°?

[Halivel]

I suspect its more to deter underwear shots when players wear skirts.

I mean... akhem, but we have items that show you underwear by default even from straight angle without any need to look up:



So I highly doubt that they had anything like this in mind when did this limitation. It's probably just some technical aspect that they couldn't (or didn't want to) avoid.