That can be part of it. Also it can be WotC's design ethos ending up being such that it gives short shrift to something I* like because most everyone else is playing this other way.
*putting myself in the shoes of this mindset
I can even give an example. I, like some other TSR-era fans, really like the idea of a straightforward fighter that doesn't need bells and whistles, they just fight. This is distinct from whether high level martials can leap chasms or wrestle death or reroute rivers (I'm mostly thinking tiers 1-2 anyways). I just mean that when it is time to fight, I just attack - without maneuvers or smites or character build whatsits. I'd like my good-old AD&D fighter (with longbow and greatsword or longsword&shield) concept to work. WotC has an option for this kind of character - the Champion Fighter (needing to dedicate stats to both Dex and Str). It is doable, but it is far and away a suboptimal build I can only use in a table of like-minded individuals who also won't optimize if I want to contribute broadly. WotC didn't have to do that -- the Champion could have been balanced to be a reasonably powerful martial option and a ranged/Str-melee switch-hitting could have been facilitated (perhaps making longbows finesse weapons such that they could use Str instead of Dex, or just making shields not take an action to don/doff) -- but they didn't because it wasn't a priority (since a lot of people like the optimization mini game of builds/feats/etc. and lots of people like resource-decision in combat). I can imagine the people not wanting epic martials can be resistant to the idea for fear that their own preferred style will lose out, designer-attention-and-deference-wise.