I think the size is for the mesh itself and the weight may not make a relevant difference in the gravity / jumping (I’m not sure how much of an effect it would make). I doubt it would be intentional but its actually quite cool how you’ve pointed this out. Hitboxes would be a big thing though.
Just did some testing:
It makes relatively no difference in the jumping by the look of it - the engine may compensate for it.
The one on the left is mirror Law who replicates my keyboard movements as a reflection (if i jump with the spacebar he will also do his idea of a jump). Mirror Law has a normal head mass. On the right is myself who has a head which is massless. From testing it seems that we both have the same jump height.
Hitboxing would be a massive difference though. Complainable I’m pretty sure some hats have larger hit boxes and using shoulder assets also increases your hitbox - therefore your hitbox may be off anyway. I doubt it was intentional and instead it was just an issue they overlooked.
I mean a work around is to no collide the heads and then have a fake head in in order to act as the hitbox but I can clearly see your point - I think its understandable why the size is as stupidly big as it is (as to make the head look better on the person) but jeez if it can’t fit through a door then we’re all doomed if we ever start making more stuff using anthro.
I think the masses and gravity and jumping they just left out as it would have little noticeable impact but the hitbox is a big flop. Not too sure how you’d fix it though as its a mesh and it has to be a relative size anyway - as such it may not be a bug but instead just something which they couldn’t find a better way to handle.