And wasn't one of the problems with the 6ft model that it left no place for Ten Forward (which is meant to be the furthest forward point on the ship, at the very front of the saucer; and wasn't invented until S2)?
Nah. The six-footer had windows at that location. The pattern just didn't match the windows of the set.
The Ten Forward set had windows like this:
narrow wide narrow (port)
narrow wide narrow (center)
narrow wide narrow (starboard)
(I'm ignoring the extra windows visible beyond the set's side walls.)
Contrast that with the six-footer's window arrangement, shown in detail in the first image of this page
I'm not so much talking about the horizontal arrangement (although that's a factor), but about the fact that the rim is too narrow - it was designed to be one deck high in the 6ft model (see this post by Andrew Probert, the designer
, with a scale sketch of how he wanted the rim to be). The 4ft model has a much thicker rim to more closely match the two-deck rim layout the set requires.
This article at Ex Astris Scientia
has the comparison pictures of the models, focusing on the rim.