Right now, when you sit on a seat, your avatar becomes perfectly frozen solid, in a pose that seems like it’d be hard to hold.
Sitting animations should really be used for this state, so that there can be a little more of a natural feel by default that doesn’t feel quite so dead-inside. There’s already evidence of other people doing this, so it should really be part of the core avatar animation system, especially considering all of the other recent investments into ensuring that avatars move and behave in a more human manner.