Comparison pics: https://www.marky.ca/3d/quake2/compare/content.html
The problem was the 3D version looked/looks just plain BLURRY.
Something about my brain is able to understand when they see a pixelated video game that it's an artifice, and give it a ton of benefit of the doubt.
I can't say it is in any way more realistic, but it feels more IMMERSIVE.
Whereas with the higher resolution one, it's an uncanny valley. Everything is too smooth and Barbara Walters-y.
Again, this is my memory of how I perceived it at the time, this isn't modern rose coloured glasses because obviously technology has improved dramatically.
At least in my eyes, might probably be also because it was the first VR headset I tried though. But the later DK2 and newer models did not capture that same feeling I had with the original DK..