The reason why they don't increase the game resolution is the same reason they had to axe the increased stash size planned for this patch. It takes up to much bandwidth and the servers can't handle it. The servers would have to send more information about the surrounding area then it already does and their old hard ware can't handle it.
Also they need to reduce hammer damage, stop the TPPK hack for hard core players, and either some how eliminate botting or just remove enigma altogether.
The skill trees need to be rebalanced as well, a fire elemental druid is out of the question. Assassin martial arts skills need buffing as well as ice/fire on amazons.
They also need to remove the respec aspect from being farmed from act bosses. This would totally cripple dueling. Someone can max a certain skill cast it (like Battle Orders, Venom, Energy Shield) - then respec while still having the skill and max just attack skills. They need to limit the respec to the den quest on each difficulty only.
If they somehow are able to incorporate all this into this patch it will make this the best game ever made... next to starcraft.