I actually enjoyed levelling (=grinding) in Lineage 2. With all the potions and newbie buffs it's a lot less downtime than it used to be. Overall, when I come home, done from work, I enjoy just mindelessly killing mobs while watching Star Trek Voyager or something like that on my 2nd screen, cause you can completely switch off. Reading quest texts or stuff like that is only half as relaxing.
However, I don't want Aion to be a grinder. I know they said you'll have the option to either grind or quest and will level similarly, but I have planned to use more brain for Aion than for L2
@Grind in general: Obviously it will always resurface. Unique content = expensive, repetitive content = cheap. It's as simple as that.