Mine is 1280x1024, so in my case the issue are games made for widescreen which need adjusting. And of course I do my best to preserve aspect ratio. And I'm always baffled by those who are bothered by black bars.
Now if the game only knows 4:3 and won't add black bars, I can deal with that change in aspect ratio, though it's not ideal. But to do the reverse of what the OP asks, squeeze 16:9/16:10 into 5:4, no way...
And if games are meant to be played at lower resolutions, fine by me, though with LCDs approximating lower resolutions, best is to go for half, or close enough, 640x480 (with black bars if possible), since 640x512 isn't in common use. 1024x768 would be fine if letterboxed, to actually have 1024x768 used pixels in the center of the screen, though center-top may also work.
And back to widescreen, always felt that they're inappropriate for playing, or even regular daily use. The aspect ratio can be fine for watching movies, and may work for office use if you want two things side by side (though in that case ultrawide is better, so wide remains poorly suited for computing in my view in pretty much any scenario), but for gaming or regular daily use with just one focused program at the time it seems to not let you take in everything at once, eyes must move from one side to the other. It was nice when the next step after (the admittedly odd, considering the nonstandard aspect ratio) 1280x1024 was 1600x1200, and I briefly even saw a couple of 2048x1536 and 2560x2048 monitors, but then they pretty much vanished and widescreen became the norm, and I kept trying to avoid it, so it's nice that this monitor still works, after 17.5 years.