Originally Posted by Seraphim
Allowing people to queue up for roles specifically would be the best approach, as long as it gives you the opportunity to play each role equally. Like it wont look to drop you in support slot unless the wait is over two minutes or something. Let a person specify what they're best and match them in to those appropriate roles. Obviously a label over the person's name saying the role they got queued for- this creates a problem though because you might have people who like builds that don't fit the meta, so by doing this you would be in fact committing Riot to the established meta at this point.
The tricky part here is that unlike WoW's Dungeon Finder, we don't have a single way of playing the game. Dungeons in WoW are designed to pretty much fit the tank/dps/heal model.
So when you match people together, you'd need some way of pairing together players who have agreed on a particular strategy or want to play in a certain way. Otherwise you might end up with two people who queued as best-at-Mid, and unless they're fine playing Double Mid, you'd get some pretty similar behaviors going on.