My impression is you have made a basic "because I value something it means everyone must think its important" mistake in your logic. Xrandr support wasn't provided for a desktop user to set their PC up once and leave it alone, it was developed for laptop users who plug their laptops into projectors a lot and want to show stuff.
The story is that some Intel exec was doing a Linux demo and realised he couldn't hotplug his monitor on laptop will all Intel parts and he kicked heads due to its unacceptability. (may not be true but it sounds good)
Things happen because ppl want them to happen, if we don't have tearfree video on open source drivers its not because nobody knows how to do it, its because nobody considers it worth doing. For example at Red Hat we can't ship a DVD player with our OS, so why the hell would we invest money in tearfree movie playing? Most Linux users playing movie are playing dodgy legal rips of content from other sources, its not something we get much paying customer demand for at all.