Have you guys never actually played a game that used a server to calculate things? WoW does this for damage, loot, spawning of mobs. Offloading things from the client is helpful. Sure, you require an internet connection, but this is 2013.
wow does that because it's an MMO and has to broadcast a lot of that stuff off to other clients and there'd be rampant cheating if people could access the loot table themselves locally. it's not doing it because client computers are slow.