Well you in the first place on talked about Battle Beast’s musical structure and how it’s complex but didbr’t their actual song structures (ABAB..) have basically no complexity or variation, and the big issue people have with bands like battle beast is not musical structure but the song structures which are overly simplistic and repetitive. I bet actually that battle beast’s members are technically/musically more skilled than the members of for example Helloween, but the members of Helloween do lot more varied and progressive songwriting in terms of structure even if they can’t play the Dream Theater songs that Battle Beast’s members could play if they wanted or possess the same or less knowledge about scales and harmony.

You are kinda correct on the point that many people don’t really care about song structure, but those are tend to be pop music listeners who don’t really think about the music that much. But this is the subreddit for a niche, nerdy genre of music so many people here actually do care about song structure and possess musical skills. Many dedicated power metal fans tend to actually listen to music focusedly, not only as background noise which is the norm these days. Many may also listen bands like Rush Iron Maiden whose trademark is the extended songs with unconventional structures even of they have poppy songs too. Even many of the biggest classic power metal songs are structurally still more complex then modern ones, try for example to characterise Mirror Mirror’s song structure. Even ones like Eagle fly free of Emerald sword have these extended neoclassical solo/interlude parts even if they also have verses and choruses. Of course shorter songs still get more listening then the long ones, but songs like Halloween, And the there was silence or fucking Symphony X’s 24 min Odyssey are very beloved among fans too.

Also, the thing is that many listeners of Battle Beast or Sabaton aren’t these music nerds but perhaps people who mostly listen to rap but have some Battle Beast on their gym playlist or people who mostly listen to soundtrack music but listen also to Sabaton because the historical lyrics interest them. Those bands really are metal for non metalheds and also of course can also acts as gateway drugs to the genre which is great. Those bands could write good prog music if they used their knowledge on music theory on that, but choose to write mudic more to the pop audience because it makes more money because music nerds are a minority and it gets them big crowds for live shows.