Because CG couldn't balance their way out of a wet paper bag. We are beta testers (even though they have a beta testing team) and they let us test it out for them to see how unbalanced or broken everything is so they can make adjustments later.
Meathead already posted that they're reviewing coliseum balance now, which could mean it'll get harder or easier.
It's the same reason why everything they release for at least the last two years is buggy as all get out. They don't test systems and expect us to beta it for them.
Capital Games Team