Pretty much this.I agree, and I think this is increasingly a problem. It almost seems as if there is a preference not to find a system that fits, but rather to wrest D&D into being whatever is the preferred mode of game for each (diverse) group.
It always boggles me when people for instance try to make D&D the "Let's run a business" or "Let's all play courtiers" game, when the rules just do not like that sort of thing. So it winds up just a bunch of rolling one skill, or like 1-3 skills vs. a set DC, and that's it.
Why would you do that instead of just going to find a system that does it so much better, with more robust options?
Resistance to change/comfort zone.
That, or a real hatred of certain mechanics. I know some gamers who refuse to play any sort of Class-based game, for instance.
The other issue is, like I said, D&D is the most widely played game. So if you find a good niche system that does what you want... you have to then find people willing to learn a new game because they likely haven't heard of the game in question.