But yeah, I had a hard time coming up with even a faux reason for why Fallout 1 would be bad. Same with Deus Ex, is there anyone who can tell me why Deus Ex is shit?
Codexers are way too forgiving of bugs in classic games that have fan patches. This applies more to Troika, but Fallout 1 and Deus Ex are still pretty rough in some areas.
Fallout 1 is my favorite game ever, but a common criticism is that it is way, way too short to the point of being more of a tech demo than a fully fledged game (I consider this a strong positive because I think cRPGs are far too long). Fans of Fallout 2's approach to the world and material also consider it tonally one-note (again, to me another strength).
Deus Ex is harder. Basically people who don't like immersive sims dislike it because it is the genre peak, but even though sales suggest most gamers are lukewarm on or actively dislike immersive sims, immersive sims are rarely criticized comprehensively because it's impossible to do so without sounding like a casual. So, anyone who cares enough to be a Deus Ex detractor (barely anyone anymore) hates it for some fussy or particular reason. I suppose a few people might dislike it because it isn't shooty enough (like a Doom clone) or stealthy enough (like Thief), ergo, the focus on multiple approaches undermines the mechanics of either actually being fun (that's kind of immersive sims though).