When I'm solo on many occations I'm waiting many 'many' minutes to get into a game. I understand you want to fill-up to a complete team, but I lose all the fun when it takes a lot of time to wait before I can join a game. When I start up a game I should b able to play.
If you're not willing to change this or if it hard to keep a balance then. I think you should punish the people that leave the game befor it finishes and not the people motivated to play a game.
Hope you will do someting about it because its a absolute good game.