First of all, I love wars. I think they are awesome, and the ROI is outstanding if you win. There are only a few improvements I'd make.
Opt in/out: necessary. Many clans do it already by kicking/re inviting players. Making it an integrated part of the game is nothing but an improvement.
Use heroes/spells while upgrading in war: this is a huge problem. Upgrading heroes is a MAJOR part of the game, warring is a HUGE part of the game. How silly is it that both can't be done at the same time. Im sure there are coding obstacles, but this should be the priority one fix.
Improved matchmaking: let us challenge each other! Instead of just searching for a random matchup, enter an 'awaiting challenge' queue. Other clans can see clans in this queue and challenge, which can be accepted or declined. Each clan can only challenge each other clan once ever.
My 2 cents. I think SC is doing a great job addressing the needs of the game and i believe they will continue to do so.
