A recent discussion in The Queue brought up the idea that perhaps WoW's Recruit-A-Friend could have been done differently. The point of RAF's bonus XP is to help you friend get to the max level as fast as possible to play with you. This is essentially so that they can experience endgame content, as opposed to leveling content. Unfortunately, WoW as an RPG relies on story for raids to be meaningful as anything other than a loot grind. Players who level too quickly may miss out on lore. In addition, quick leveling also means less time learning character skills needed to raid, and we've all seen the guy who bought a level 85 warrior but still didn't know how to taunt.
But what if leveling speed isn't RAF's problem? What if the problem is the concept of levels themselves? If you want to play Mario Kart with a friend, you just jump in. Skill becomes the only barrier, and fun gameplay mechanics take over the grind. It also makes it a lot easier to close the gap between you and your friend in a fun way. The same goes for most FPS, RTS and fighter games ... Only RPGs put this artificial barrier in place.
However, removing level would affect other areas of gameplay. Quests could be lore- and appearance-centric, rather than grind- and gear-centric. Since all players are at the same level, queues for instanced content would go down and it would be easier to get bodies for raids. The rest of the game world would also be easier to expand and utilize, since developers wouldn't need to worry about sheltering level 15s against level 80s. It would, though, make alts more common, which may be problematic in gear acquisition for people's mains for those who raid.
Would you play a WoW without levels, or is there something about levels that is still needed?