It's one thing to create HD stuff for TV.
It's another thing to do it for a 70ft. screen.
We've had HD on computers for years now. But when you blow it up to TV size, it doesn't look as good because it blows up the imperfections as well. We eventually got the processing power to do better compression to make it look better. But you can still sometimes see issues, especially on lower-end stations where they compress more to save bandwidth. It gets blocky, splotchy, etc. and its more noticeable on a bigger TV than a smaller one, even with the same number of scan lines or pixels. Because the pixels are bigger.
Now, imagine a screen the size of Soarin'.
The way around that is to use multiple high-resolution digital projectors, each dealing with a different part of the screen, and having to calibrate them properly to align perfectly, and having to do that periodically.
Disney IS moving to digital projection, and high definition will need to be part of that. Muppetvision is the first to get it. But the technology does not come cheap, and some of what Disney has now is custom already.
