I keep explaining why but people keep mentioning it...you CANNOT enclose the outdoor portion of the track and keep the existing infrastructure as is.
First, and most importantly, you would go deaf. If someone doesn't believe me, watch an on-ride video of RSR and listen to how loud it is when you go underneath the 'cave' where the on-ride camera is. If it's THAT loud and you're only there for, say, 1-3 seconds, imagine how it would be for a minute and a half.
Secondly, it's a matter of physics. What happens to skyscrapers and bridges that are high in the air? They are allowed to sway due to the elements and the constant shift in weight and movement the buildings have. If skyscrapers were built as completely standing still, a rainstorm would pass by and probably topple the building. Same exact reasoning goes for TT. If you put that on top of the existing infrasture, it would create additional weight. It's just not feasible.
Thirdly, think about it: you're going 65 mph. What could you create that's extremely noticeable or noteworthy when you're blazing by at 65 mph?: Nothing.
Lastly, I can imagine a lot of folks would say, "Well, they can just enclose the entire outside track by extending the building." True, but it's not possible at all. It's arguably the biggest artery when it comes to CM traffic flow to and from backstage (especially for those CM's in FW) and it's extremely important for service vehicles and the like during third shift. There's NO way they can do that at all without some major infrastructure changes.
Definitely agree about Universal kicking WDW though. As a friend of mine told me once...Before, Disney (in general) was the top dog, respected by every other company and the ones who held the bar for excellence. Now, companies look at them as the laughing stock in terms of technological advancement and other issues.