I wouldn't mind slower leveling, if only the process of leveling up was made to be more entertaining.

Currently, the only way to really level up efficiently is through Guild Leves, which are all incredibly boring. Seriously, Guild Leves are the single worst quest system I have ever seen in any RPG ever, online or off. All the other quests in the game are fine, but Guild Leves just flat out suck. So maybe if there was a fun way to level up efficiently that didn't involve Guild Leves, I wouldn't mind if the rate of progress was slowed a bit.