I don't get all the hate. GMR is a ride that guests either never ride, don't like, or think it is outdated. My SIL hates it and refuses to ride it, I think it is just ok and could take it or leave it, my friends who come down yearly never even bothered to ride it until I dragged them on it. They said they were glad they did it for parts, but didn't need to do it again. It scored low on surveys. So why not replace it? It seems the tech is being moved away from and probably getting expensive to run (think Disaster), so again why not replace it. Putting something new and awesome there I think is a great idea.
Disney is FINALLY paying attention to a park that needs a TON of help and everyone keeps hating on what they are doing. Adding 5 new attractions in 5 years with 4 of then being in brand new lands. Adding a larger footprint to the park and leaving expansion pads for later additions. I get they waited too long and should have done this year's ago, but outside of that complaint I don't get all the hate.