I can see changing dungeon respawns to 5 minutes, as well as dropping any of the 24 hour+ respawns to something less, and that's about it.

The drop rate on most items in the game is fine. It can be frsutrating at times, but that's usually just bad luck, and not bad game design. Unless you're talking about the Defending Ring. That's the only drop I can agree with you on, though even then a 50% drop rate is still a bit much.