Don't agree here - I'm happy with the amount of XP gained from mobs and the amount of time it takes to kill same level mobs with decent gear - Mob Grinding should be long and arduous - It is in any MMO you will play - the problem is the lack of XP from Quests - Mob Grinding is more efficient - It's also as you said the lack of other content that provides reasonable XP for Grads.
IMO the issue is not necessarily that the mobs don't award enough XP, but that there is basically no alternative. In other MMORPGs there is always a handful of ways to earn XP efficiency. A classic example of this is running dungeons with your friends in WoW. I think that raising the XP earned is more of a compromise for the lack of variety in XP grinding.