I thought, while crouching, a users name tag should vanish from sight, making 'sneaking' a lot more fun

The character itself can still be seen and selected, but you'll be able to hide behind things, or in bushes, and not be seen.
If you're camouflaged on terrain with swaying grass or something, you may even be able to stay hidden in plain sight!
Mostly pointless, but it would be great for games like hide and seek.
Anyone play minecraft? If you hold shift, your name disappears. That alone has gotten me out of some bleak PvP encounters.