Actually the QfG 2 they've posted is a fan made VGA-style upgrade done recently. The original from Sierra was actually half the resolution and in EGA (and thus 16 colors). Also UQM has had some work go into the graphics for that as well through resolution shaders from what I remember.
I sort of think the "graphics > gameplay" argument is a hollow one. It's sort of like saying you can't watch Casablanca or the Leslie Howard version of the Scarlett Pimpernel because they are in black and white.
While some of these games are not that old (TF2 for example) and thus have no problem finding an audience even from a modern-only crowd, even with 320x240 resolution and 256 colors many of these titles have stood the test of time very nicely. Star Control 2, which I've mentioned a few times here, is an outstanding sandbox title even until this day, as is Daggerfall and (less with a narrower focus but still sandboxy) Quest 2. Any of those three titles easily offer more game time (and more *satisfying* game time) than most major studio releases today. Flashy lights are nice but only 40 hours to complete a title, at a charge of $50-60?
There's a large contingent of gamers who are increasingly less concerned about looks and more about playable time. Look at Minecraft, a megahit by any standard with 12 million purchases. And yet the graphics are in the Quake 1-2 era (mid 90s). That doesn't seem to bother anyone. Of course since it generates a world up to 1/3 the size of Earth, it still manages to tax even some Core 2 and later systems.
But there are other games would comfortably fit into this group of older titles that (while not free) are recent releases with similarly "poor" graphics, such as FTL, Shadowrun Returns, McPixel, Gunpoint, etc.. All well received releases and yet they have graphic fidelities ranging from those seen in the early 90s (Pixel) to the early 2000s (SR Returns).
So long as graphics do not render a game utterly unplayable (like the old strategy game Bravo Romeo Delta, where you couldn't even read the names of the towns) and the gameplay is there, there will be an audience and they are willing to pay, let alone download a title at no cost. Good Old Games is proof of that.