If we're going the hardware route:
- players had to buy good hardware to play Unreal/UT;
- players had to buy better hardware to play UT2003/UT2004;
- players had to buy even better hardware to play UT3;
- players have to buy a hell lot better hadware to play UT4;
see the trending? Each engine generation will obviously lead to the need of newer and better hardware, there's no stopping it, and in a few years almost anyone will probably have "low-end" hardware by the standards then, but which is more than good enough to play UT4.
So yeah, using the hardware alone as a reason to not do something in a newer engine, is rather silly.
And this new hardware might be needed not only because of its superior raw performance, newer hardware generally has new built-in features in itself which only the newer engines can use.
This is why while you could buy the best graphic card in the market, it doesn't necessarily grant you a superior framerate in UT, but it certainly allows you to play any newer far more detailed and heavy game smoothly, since UE1 does not use any of the hardware features only new hardware provides, while UE4 for example does, hence being able to do what it can do, and do it with a good framerate.
Having that said, it's true that the newer the engine, the harder is to make anything with it, and Tim Sweeney already talked about this some years back, namely on the costs of such an increased complexity, as newer engines grant the possibility to do far more amazing things, but the people remain pretty much the same so you need bigger teams and even more development time to do anything of worth at all with these, and the costs of that are increasing.
One way of tackle these costs is with microtransactions.
This is why many developers are returning to the roots.
"Minimalist" design overall in games is not much about the style itself, but rather what just a handful of developers are able to make in a shorter amount of time, and still make it pleasant to the eye concerning the quality standards of nowadays.
This is also why guys like me still enjoy doing one or another thing for UT99 for instance. It's still one of the best games I ever played, with a shit ton of content to enjoy, from absolute garbage to jaw dropping, and despite all its technical flaws and limitations by any standard nowadays, it's one of the only platforms someone like me actually has a bit of free time to dedicate to, rather than using something newer which, while it would be far more future proof and would look better, it would take a lot more time to do anything at all due to the sheer amount of time the artist side of things alone would take in comparison (textures/skins, models, etc).