1) Create more facilities for community policing of bad behaviour
- peer-driven player rating system (obviously need a UI for rating each player after each game)
- ability to customize your matchmaking preferences to filter out ranges of ratings. This should bracket your tunable range to YOUR own rating, so you get to play with people of "like personality"
- each season, reward highly rated players with swag like Feats of Strength, portraits, BlizzCon tickets, honorable mentions on the forums, super honorable mention by shoutcasters at WCS, a "star" next to their portrait that lasts a month, etc
2) Change ally creep to be buildable
3) Randomly getting matched with buddies well below your skill range sucks. Expose a tunable that will allow you to tighten your matchmaking brackets (at the cost of potentially much longer wait times). Let each player decide for himself the cost of being more accurately matched.
4) Friendly fire sucks. Naive idea: Disable ability to force attack allied units, only allow attack on allied structures. If your unit or building is attacked, you now have permission to attack your attacker's buildings AND units for 5 mins. Thoughts?