Shields do have block %s at higher levels. Not a huge amount (1% is all you're likely to see), and certainly not enough to change the value of shields much, but it's there.
I actually prefer the offense-over-defense style of combat right now though, and I'm not in favor of pushing 'tank' gameplay (everyone is forced to attack the heavily protected guy just because); it makes combat extremely predictable (and exploitable) against AIs and won't work at all in the PvP elements that the game wants to allow/encourage.
