I can say the same of the few places I mentioned in VI, since you're often times climbing up the side and then wandering into caves inside the mountain, so it s not like its a texture copy paste job like your describing. The Veldt Mountain cave is two screens max as well, and the other mountain regions in the game actually do give you views of other things, like the Narshe Mine caves leading out to different parts of the city, and reaching the peak actually gives you a view of the city of Narshe from the distance. Even back to FFIV, looking into the background of Mt. Hobs and Mt. Ordeals, shows forest and mountains in the distance. You are getting the view you crave, so I can't quite fathom your argument here.
I can agree the Calm Lands would have been better served if the team actually had the time to implement visible monsters on the field, yet even then, I feel the Calm Land is pretty bland visually speaking, I feel the same about Bikanel Island as well. Plains are boring to see in general, and I will never understand how people can live in some places without an ocean, forest, or mountain in the backdrop, maybe that's just me though.Although the Calm Lands were very bland, admittedly. I think the problem with it was that X still had random battles. XII had several large flat areas and XIII obviously had the steppe, and they were very cool, what with big monsters roaming around making it a more interactive experience.
Also, I might have to admit to Wolf Kanno that I have started to like XII more and more in hindsight.