EPT1. The cheese factor. In 2v2 it seems to be all about cheese. Cheese one player out of the game and gang up 2v1 on the remaining guy. Starcraft unlike company of heroes and some other RTS games does not convert to AI when a player bails early. In 3v3 the maps are big enough to buffer early rushes and cheese.
2. The weak partner factor. You can survive if one of your 2 teammates is not up to par but you will not likely survive a bad partner in a 2v2 match. 2 good players can win vs 3 average players.
3. The lone wolf factor. The team that plays together almost always wins in 3v3. 3v3 does not eliminate the rogue knucklehead partner but it does discourage it. Defend as a team, attack as a team and watch each other's backs and you have a good chance to win.
In short i think there are a lot of interesting strategic possibilities in 3v3 and it is an underrated way to play this incredible game. I look forward to some other points of view.
3v3 is a blast!
