This view:
I know it made sense back in the day, as you were boarding the StarSpeeder through an actual movie set, what with the Director's chairs for Threepio and Artoo, and the callsheets stapled to the bulletin board and such. The AT-AT was meant to be a movie prop....you're walking onto the set.
But those days are gone. With Star Tours: TAC, you're no longer on a movie set, but walking directly into a Star Tours Depot. It only makes sense for them to create a few panels and cover up all of the unsightly innards.
Also...are the water cannons still working? Last time I saw them active was in 2011. My last trip in July 2013 they were off.

I know it made sense back in the day, as you were boarding the StarSpeeder through an actual movie set, what with the Director's chairs for Threepio and Artoo, and the callsheets stapled to the bulletin board and such. The AT-AT was meant to be a movie prop....you're walking onto the set.
But those days are gone. With Star Tours: TAC, you're no longer on a movie set, but walking directly into a Star Tours Depot. It only makes sense for them to create a few panels and cover up all of the unsightly innards.
Also...are the water cannons still working? Last time I saw them active was in 2011. My last trip in July 2013 they were off.