The reality is that most folks don't stay for more than 5 minutes in front of any layout at an exhibition. At the larger exhibitions such as Warley, there is not time for more.
So I think that there is definitely a role for layouts where those 5 minutes can be focussed on some top quality modelmaking (such as Nicktoix' buildings) rather than be distracted by too many trains rushing past.
The snag, of course, with 4' long layouts and proscenium style presentation, is that only about 3 people at a time, whatever their height, can look at the layout at the same time. That rather limits the show's attendance figures.