Interesting, a friend of mine made the same comment in 96 when I was literally drooling over quake shareware. I have to admit that QTest did look "better" because there were no monster but only the eerily lit labyrinths which where a sight to behold.
Quake's models were nonetheless very well made for the time, especially when taking into account that the people responsible were not well versed in creating such content. Take a look at the shambler when he walks - weight and power, a little master-piece. Only stupid looking character were the small knights with their dorky sword attacks... seemed like the player was magnetic and magically pulling them towards him.
Doom and Wolf had the advantage that every actor is a near "pixel-perfect" beautiful, comic style cut-out only being scaled and, in Doom's case, shaded. The viewers eye is restricted to the xy plane which further helps the very simple world geometry to hide its brutal, but effective, minimalism. Add to that, the already mentioned, low resolution which perfectly touches up the rendered content and you have a winner... especially in Doom's case.
Restrictions are the minds/brains best friend which successfully creates what pleases the owner the most - it's a combo that even the most bunga-bunga-mega hardware in the world has trouble to beat.
And as a quick ode to 2.5D goodness...
I still have a source mod of ChocolateDoom lying around, which I did in 2012, that renders the game in full 24 bit color(+colored sector "lighting" and crudely hacked transparent masked walls/sprites) and it looks dandy.