There is another thing - low res games were played on a CRT monitor that had a natural smoothing of pixels. If you launch any old game on any modern monitor it will look way worse than it used to be.
It is looking strange in cases of GUI with many details, but in old games it work mostly ok.
And unfortunately it was unavoidable, because many old games don't accept modern "wide" resolutions, in best case just cut screen, so wide "ears" remain unused.
But with hardware smoothing, it is possible to run with top strip cut, which is sometimes better than with black "ears" and with unused screen space.