I join this discussion to agree with all: there are too may players that simply aren't able to play in team! They're random-placing, spam-placing and occupy all the space you need for doing a better defence. So many nubs that certain games are simply frustrating and all you can do is /leave and hoping that the next one is simply better.
I'm ok to limit placing towers: in 5x5 spaces we shouldn't be able to build 3x3 ones. Fire, ice, mage and quacke stacking should be strongly checked, 'cos I saw many times two fire at start, one placed on right, one on left, and it's not good.
Also, as the game proceed, you need to upgrade your towers. But many placers just have not upgrades unlocked, so you're stuck with 2LVL TNT as you can't choose the path. I think they should be unlocked, once the game is getting long and armageddon is coming.
Voteckick would be great, not only for premiums, but for all. Many players, as said, are just teaming with other squad...
I also really enjoy if there are 4vs4 or 2vs2 games. Otherwise, a 2vs6: I'd really like to try it just to proove that good placing and collaborating is more effective than spamming monsters and towers. I'm able to win almost every game with my friend sending 2 waves of pigmans with 2 waves of witches togheter with my friend, after 7 minutes of the game, just the time to get enough exp and coins. The 2 vs 6 could valutate the "ability" of single players, when the game is starting. If they are winning many games, a dialog should ask "are you sure to get against 4-5-6 players? You're only 2/3 in your team: Y/N". And I would say SURELY YES: finally I can place towers as I want, getting many monsters 'cos many players sending enemies and getting rich, 'cos a double price is very rare to see...