I know that games of that time period - D&D more than any - were dealing with an "all about combat" perception, and Champions! emulated a genre with similar issues.
But, those were very much outsider impressions.
Being all about combat isn't the sole or primary problem though. The issue HERO has is that it ostensibly attempts to emulate superheroes, but does so via a system that, in practice, doesn't produce results that feel like superheroics, but rather like highly-tactical combat or precisely delinated abilities, where virtually all abilities are carefully pre-defined beforehand, and working out new stuff on the fly takes a while, and stunts and so on (a mainstay of comics and movies) are not really very workable.
I mean, we can turn the clock back to 1990, and pretend that systems don't influence the feel of an RPG, that a "True Roleplayer" can roleplay through any dreadful or inappropriate system, but that's a bit silly, frankly. HERO was a victim of dull and subject-inappropriate design, not a victim of being "so good you never need another". I mean, I have to ask though, have you actually played other supers RPGs? If so which?
(I'm sure there are people who have never played anything but HERO - but there are people who only played d20-based games, no matter how dreadful they were for what they were trying to emulate.)
Name 72 other effects-based systems.
You know what I mean. There are certainly plenty of others that are either primarily effects-based, or had an effects-based subsystem for dealing with/costing superpowers and/or magic, and I'm not going to argue the toss over
exactly which ones count (M&M, BESM/Tri-stat/SAS, Godlike, GURPS superhero plug-in, some FUZION variants, off the top of my head and without delving into obscure stuff).
This is probably my greatest contention with D&D. It does D&D fantasy exceedingly well, but I always find myself fighting D&D when I wanna do anything that veers too much out of its brand of fantasy RPG. At that point, it's usually easier to find another system that does the sort of fantasy RPG I am looking for when brainstorming a particular campaign/setting idea.
Definitely agree that this is the biggest issue with D&D. I feel like in some alternate universe, 3E, instead of trading on nostalgia and going with weird ideas like trap feats, built a really strong basic game-chassis for a certain kind of fantasy RPG (whether modern or ancient), without the extreme-ness of D&D, and let D&D be merely "one take" on what it could be. Certainly 3E made some attempts in this direction, but these extremely linear nature of levels and HP and bonuses and so on meant that it doesn't work for most stuff (and this lead to a lot of d20-era RPGs being super-clunky, I'm looking at you d20 Modern and Spycraft).