+1. Aesthetically, bolsters (or ferrules, or tsuba, whatever you want to call them) just kinda finish the handle. It doesn't matter if it's just a thin cap or something more robust. Metal, micarta, wood, horn... whatever works the best with the other components of the entire knife.
Mechanically, I like the idea of having something to protect the face of the handle material.
Not that I've ever come close to hitting a stone or anything :O.
Also, I've noticed that for some reason, the joint at the front face of bolsterless handles is always the first to lose integrity, allowing water and other nasty stuff to start undermining the epoxy bond. Like ice in a sidewalk crack...just keeps getting bigger. Not that it can't happen on bolstered handles as well, it just seems to happen quicker on those without.