IN GAME VOICE CHAT
If you want to improve the experience of solo queue vs premade teams I believe the solution is simple. You must create an in-game voice communication system. A major difference between premade teams and your average randomly generated teams is that the premade is almost guaranteed to be linked via external applications like Skype or Curse. Before playing league, (Season 1), I was a huge DOTA enthusiast, and naturally when the WC3 trend died I looked to the most similar games of that time which were League of Legends (LOL), and Heroes of Newearth (HON). The main thing HON had going for them was that they had a built in chat system. This system was even as sophisticated enough to divide your chat options between lanes to minimize unnecessary chat, while leaving the option open to communicate with your team across the map as well. They had the luxury of INSTANT communication. This made the game far more fast paced, and the teamfights much more well coordinated, being that you could far more clearly indicate your intent via mic rather than keyboard. I am sure with all the advancements RIOT has made since the release of LOL you guys can manage to scrape together an interface with a similar design.