Seeing as there's a dude who's multibotting 100 accounts and have 100+ characters at lvl 90 with the playtime of 1 character I don't see the point of it.
Achievements should be given to someone who's done something incredibly hard or shows incredible dedication, leveling is neither. Feat of Strenght sure, should also be a feat of strenght to have 1 year played on your character, 2 years, 3 years and so on. Even thinking that leveling should somehow grant you a title or a mount is strange...
On topic, there should be a feat of strength I see no reason why not. It IS a lot of work to get all the way to 90 on every class - It's not worthy of a real achievement because obviously that would be unfair for people trying to get every one of them, but it definitely deserves a feat of strength and a title.
Why stop the achievement at 5 chars? It seems to make logical sense to have one for every char. Also, how are achievements like 'The Insane' any more deserving of a feat than all characters maxed?
jesus you really have one of every class at 90? are they all the same race maybe that has something to do with it
It should reward some titles, like
Character, the basement dweller
Eternally Virgin CHaracter