There's something slightly unnerving about Horizon's avatars. While it's more or less understood that floating avatars are the best match for current modes of VR locomotion, thus the lack of legs, there's an important difference between something like Rec Room VR's floating avatars and Horizon's: The former's are far more abstract, and thus look more natural in their omissions.
Rec Room's avatars consist of floating hands, a floating head, and a floating torso, all disconnected. It doesn't seem odd that they don't have legs, because their other features are more removed from the human form. Facebook's, on the other hand, are fully-formed cartoon characters from the waist up, more on the order of XBox Live avatars. This greater detail makes the lack of detail elsewhere look out of place, and even slightly disturbing given its imposition on a human figure.