It's also better pre level 40 aswell, you just must find a place that suits you well for your class. There are mobs with less HP or weak vs ranged or magic attacks for example, so not every mob is good for grinding. I myself play a ranger and most of the mobs have either too much HP or too much defense...but there are also weak ones
For example, level 25-30 i found incredible good to level by hunting Life Reapers in the abyss (they are like level 27 or 28, very weak mobs which gives 10k exp...you also can get the repeatable quest at level 26 which is awsome...being able to make even a level in an hour). Level 32-36 Fearful Spirits are weak aswell in the abyss. If you don't want the abyss because ganking can get really annoying you can grind mobs like...spiders are usually weak, so octanu's lair was a good place for lvl 26-27 to level 31 or so.
With that being said, grinding is good if you know how...you just must find which mobs are best for your class, and you can find that info at Aionsource.com
