I'm not a massive fan of Billy's tone, but that's who he is and that's what he does, and it seems to be a big part of whatever band he's in. As soon as you hear it you know who the bassist is. There are plenty of singers whose voices I don't particularly like, but you know who it is as soon as they open their gob, and that individuality is a large part of their persona - Axl Rose, Ozzy, Liam Gallagher, Brian Johnson. Same principle, I guess. It works. *shrug*