I really do like Doom and I've played it more times than might be good for me 🥺 But you're definitely right about the colors.... It's not that they're bad, but they didn't really explore the spectrum that was available at the time. So what they have left is kind of limited
They kind of worked themselves into a corner with all the red and flesh colors, you know? Funny you would mention Doom 64 as I love its colors and overall look... And was just playing it too
fanmade stuff also has a tendency to be beautiful w/ custom texture packs but i don't wamma judge those because we had years of hindsight and hammering technique. Of course stuff like the Eviternities or Ancient Aliens look more visually impactful than Doom 2
I really think Heretic did a great job taking a fantasy setting and giving you every kind of landscape it felt it could manage. Blue skies and water are especially nice along with the colorful weapons. And the stained glass. Brilliant.