It's not the rankings that make it more serious, it's the need for cooperation. In WCS, GG and Pub, you still play fairly independent with some cooperation to win. But in ZM, cooperation is often a necessity.
I'm all for removing rank for other reasons, but it's not the cause of the tension on the server most of the time.
I don't have an issue with fast zombies on escape maps, but I do have issue with their ability to avoid knockback by straft running (holding W and A/S while angling with mouse). It's this that really dooms most people on escape maps.
I also like parachutes. I think it adds something to the gameplay, albeit too much on some maps like rooftop escape. Are there variables in the parachute mod you can change?