Disney just doesn't do things quickly. If I could find the quote I would, but a previous poster put up how they like to spread construction expenses over multiple quarters. That is exactly right. Plus, there isn't much bang for their buck in doing it quickly. People plan Disney vacations .5-1.5 years out. The vast majority of planned vacations are already locked in, whether they rush to complete Tron and Rat or not. Spreading construction over 2 years is cheaper, they take a smaller hit in any single quarter, and they dangle a carrot for people to plan another trip 2-3 years out to see what they missed on this trip.
For the APs and DVC type folks, they are coming anyway. So if you spend to open Rat quickly, you are going to get the same locals to show up now and you will if you don't spend so much and open it in 2 years. It's a complete wash. To get those dollars, you need to do 2 things, keep them renewing, and keep them spending when they do show up. One way to do both is to introduce new things at regular intervals. With Pandora last year, Toy Story this year, Star Wars next year... those bases are covered.
In the end, there is no point in rushing these or even to move at a regular pace. Slow and steady pays the most for Disney.
