It sounds like you want to obliterate pool mining all together. Everyone go back to solo mining, problem solved, :p
Even if you keep all the pools under 50% two pools combined would be well over 50% which can do far more damage and faster than 1 pool over 50%.
And it sounds like you're a selfish child who doesn't know how bitcoins work. a single entity needs to be in control of >= 51% of the mining for the double spending attack to even be feasible. 2 entities at 30% won't do shit.
They can work together and then yes, it is an issue. It is more difficult for an cracker and hacker to take over two pools. I would like to see three or for roughly equal size pools personally and all secured and ideally not running the same stock code (or craving and hacking multiple pools would be much easier).