1. Deus Ex, is arguably one of the best games ever made. I know many people who do not enjoy it's ancient looking graphics and glitchy atmosphere, but if you are looking for quality, Deus Ex is unique and unrivaled in it's areas of skills, stealth, and storyline. Other games have matched and surpassed Deus Ex in individual areas of skill-sets, stealth, and storyline; but never have I come across a game that does all three so efficiently and seamlessly as Deus Ex. It is truly a game of options, and compared to the modern trend that so many games fall into, a trend of babying and simplifying, a trend of giving the illusion of choice but ultimately offering nothing more than horns or a halo (Fable, I'm looking at you), Deus Ex is a unique experience and a worthwhile game that I have invested many hours into. I would also suggest the HD mod that is available that sharpens and clears up the game's older graphics, as well as Shifter Mod, which introduces new innovations and gameplay characteristics, making Deus Ex mechanics almost entirely redesigned, offering multiple new choices in gameplay and tactics.
2. Morrowind is still considered by some to be a better game than Oblivion. Though personally I cannot imagine and Elder Scrolls Game competing with a healthily modded Skyrim, Morrowind was less immense, but slightly more bulkier. In essence, you could compare Morrowind and Oblivion to GTA: III, and Vice City. Vice City had significantly less script and storyline, but was a larger playing area and offered a bit more sight-seeing than GTA III. It really comes down to personally preference, however, to say that Morrowind is no longer valid after the success of Oblivion and now Skyrim, would be denying it's rightful spot as the fatherhead of the series. Morrowind is still an immense and detailed environment and was a complete redesign from Daggerfall. I would even go so far as to suggest downloading DOSBox, and playing Daggerfall, and maybe even Arena. If you are interested in Storyline and an over-arching feel of the world, the entire Elder Scrolls Series is Golden and worthwhile. (especially if you are taking notes in class, and have to have a game running that is easy to Alt+Tab).
3. I will put KOTOR 2 and KOTOR in this group as KOTOR Series, and the KOTOR Series is one of the greatest RPG's ever made. It is official Star Wars Cannon, and is fun. I preferred KOTOR 2 over KOTOR simply because of the ability to manipulate and transform your allies (not to mention avoiding the Selkath, those mumbling bastards...) but both games are great and I would suggest that any gamer who enjoys a solid and fun RPG play these games. It is a shame, in my un-humble opinion, that the series went to MMORPG format, since KOTOR 2 was hurried and released before it's true completion. It would have been nice to have the series tied together and finished with a proper trilogy, in true Star Wars Format, but luckily, with the Restoration Mod, and a still active (though diminished) modding community, the KOTOR series has been reborn multiple times.
The one beautiful thing about all three games you mentioned is the capacity for mods. Deus Ex is the weakest in this category, but still has a solid core of a few really good mods. This allows for multiple replays and an unending variation. KOTOR and KOTOR 2 still have active modding communities that still release armor and level designs, and is one of the most dedicated modding communities on the web. I would suggest playing these games, and then modding the hell outta them. The last time I had KOTOR 2 installed, I had around 4GB of Mods attached. I hope that you can see the validity and value of these games as historic, iconic, and enjoyable and not be so shortsighted as to see the quality of the graphics and assume they have somehow lost their appeal.