single player and MMO are very different in design.
Single player, calculation are made on personal computer (or console), there is no latency beyond CPU power and RAM speed.
MMO, calculation for hits, position, everything are made server wise. this ensure their is no cheating. Latency issues are very real.
This force company making MMO to take design decision. (such as spell range, global cooldown, auto aim). You don't have to aim your fireball in wow now do you?
It's not that they want to try something fresh and new. I'm sure bethesda (and us) would wish nothing more than make a skyrim MMO but it's not possible, they HAVE to rethink their whole game design. Guild wars does suffer the same limitation too.
The most experinced and successfull MMO company is certainly blizzard. Even they are not capable going around the latency/server calculation issue.
If you want to play a heavily multiplayer game, you have to accept the technical limitation of the real world, and embrace the "MMO design" rules.