I think you're spot on with your analysis. This is writing I'd expect to find in the Wall Street Journal Cels from some series have always been relatively inexpensive (think American shows like He-Man) because of the plethora of quantity on the market.
I also agree that, in general, we see buyer demand decreasing for all cels, as the younger generations are not familiar with the shows and so the interest is not there. Unfortunately, as you indicate, there are notable exceptions to this phenomenon, namely, very popular shows that still have a cult following. A subset of folks who are now adults from the 80's (earlier?) who have the economic means to drive prices up for important examples of works from these series are keeping the market for these pieces high. Case in point - quality Macross cels are limited in quantity, for reasons you identify in your above post, and, by observation, they are now *more* expensive then they were in the 90's or early 00's as dealer quantity has dried up and private collectors (attempt to) cannibalize eachother's collections.
With that said, I'm looking for great images of Misa Hayase from SDF Macross TV. PM me if you've got any.