One reason to have 80 levels might be that they want everyone to be able to experience every zone while leveling AND be able to PvP some, do some WvWvW at the same time. So you don't level to fast and won't be able to experience every zone as you're leveling.

Some guys, probably a lot WoW fans that'll try it out, are gonna do like they do with WoW. Rush the continent and play "end-game" (for them) which is PvP, Elite DE's, Dungeons and WvWvW, they won't be experiencing all zones and all that if it's to few levels maybe. Idk, just a shot into thin air