I'm not a big Asia fan either. They were intentionally AOR type music, not prog. Which was disappointing considering the pedigree of the musicians involved. But even the prog groups that were around at that point were also leaning towards pop - Genesis, the other guys in Yes, etc. I think part of it was the "uncool" factor of prog at the time, and the desire to make big selling pop music.
Heck, even classic rock bands were playing simpler, money grabbing music - Jefferson Starship for example. And later Aerosmith, Heart, REO Speedwagon, ZZ Top and Chicago followed that formula too, IMO.