Then how about just making mono pillars produce 2Q/turn instead of 1?
I have been playing this game nearly since the beginning. I have NEVER had a rainbow deck, because I like being different. But the temptation is there. I know that rainbows dominate, and it's because getting 3Q/pillar/turn is just too much.
When I have only 2-3 elements in my deck, and I still think I would be better off with quantum towers, I have to recognize that they are overpowered.