Since stat overlays have been introduced it has been easy and quick to estimate a players skill with resonable accuracy in pugs. This allows a players in the loby to be split into the most even teams posible, this is very good when even teams are possible.
The problem occurs when there is an odd number (3 is the worst) of weak or 'pro' (pro is less of a problem) players in a loby as these cannot be evenly distributed on each team, resaulting in one team being very likely to win (and the other lose), with everyone knowing it. This requires either that players be kicked or quiting, or that the weaker team agrees to play knowing that they will most likely loose around the 10 to 18 min mark and loose ranking before the game starts (I really dont like to do this).
The unranked option would be useful in this case because it will allow the game to happend and will still be fun upto a cirtain point in the game regardless of skill, yes this not even close to being ideal but still its better than the current situation. One problem is now there is little insentive not to RQ after a few deaths.
Since there is no longer the threat of a exp drop to the stronger team this will ecourage them to use weaker (but possibly more fun) demigod builds to help ballance the game and attempt to make it changing for both teams. Fun or game to try build out would also be possible.
I dont think this could be too hard to impliment, just add a dropdown box for ranked or unranked under the game options that would trigger the game resault not to count. Could the under 3 min dissconect code (or invalid gamesate) be altered to do this?