I believe that vampires were nerfed b/c the vampire queen was nerfed, b/c people thought the VQ was overpowered b/c somebody was cheating
Ethereal never made sense to me for vampires, though. They're not like ghosts.
Invulnerability - a natural prot of 20 - would seem to make more sense to me. But that would be even more powerful than ethereal, I think.