I'd like to understand how network latency is related to framerate. This forum will never cease to amaze me.
30fps is NOT smooth, period. Even with 500ms latency it doesn't matter, it is not smooth. 60fps is not a waste for MMO when you are playing in a low populated area or during cut-scene. Off course in town or during massive events, I don't expect any graphic engine to be able to render tons of players while maintaining a solid 60fps framerate even with high-end hardware.