With regard to MK, just because the other parks need additions more (much more, we agree), that doesn't mean MK isn't in need of fresh blood. I agree that New Fantasyland was actually the correct addition to give this infusion and, more importantly, add capacity. It's unfortunate that its the only major thing of substance in 20 years, though MK has seen its fair share of minor additions throughout the years. People just have a pent up need for more because MK should get a new "E Ticket" every 5-10 years, IMO, and has been lacking for too long. The real test is what's next for MK, if they stop with New Fantasyland, then the issues are only going to get worse.
What they need to do, IMO, is add immersive (but not necessarily thrilling - think POTC and HM, not RnR) to the other parks to help boost their draw and time consumption and take the pressure of MK. But, they are so far behind the ball with this, and nothing appears close to being green lit.