The client-based MMORPG architecture is essentially solved. If you're paranoid about security you can always be like Blizzard and run the Warden to spy on your users. Until we've discovered a way to transmit information faster than the speed of light, there's no reason to do it in a server-based mode. Even at light speed + infinitely fast server/client you'd expect a game like WoW to have same issues as FF14 about 3% of the time (0.01s lag versus 0.3s lag) if it ran on the same model, and nobody would consider WoW's PvP as acceptable if an ability like Ice Block failed with 3% the frequency compared to say Hallowed Ground failing in FF14 (which can be quite often). Note that here failure means you used the ability, and was charged the CD, but it did not activate.