That suggestion to do an Star Wars version of Ultima Underworld reminds me of the Sith Temple levels from Mysteries of the Sith. If someone could do a game which combined the best parts of MotS's Sith levels and Ultima Underworld, that would be an interesting experience. It would be rather System Shock-like too, because of the futuristic setting and the inclusion of a lightsaber (System Shock had a lightsaber-like weapon long before it would appear in Jedi Knight, and a year before Dark Forces).
Another first-person RPG I think should have a Star Wars rendition is Morrowind: why not use it as a template for a Star Wars game set during the events of Tales of the Jedi? Of course, the gameplay would be updated, and the lightsaber would have more functionality than the sword mechanics of Morrowind.
Other games that I also think should have been mentioned are Deus Ex, No One Lives Forever, and Half-Life. There are elements in all those games which I long to see in a Dark Forces sequel. Dark Forces after all began where the player assumed the role of a highly skilled mercenary, so the gameplay of Deus Ex and NOLF would suit the Dark Forces series very well. Additionally, the freeform gameplay, multiple choices, and map design of Deus Ex would combine well with the elements of Dark Forces. And Half-Life, because of the cinematic aspect, character interaction, and level design.
There are some other RTSs that come to mind which I'm surprised haven't been considered: StarCraft and Sacrifice. StarCraft, because of the emphasis on factions being unique from each other, and the storytelling (well, the first StarCraft's storytelling, anyway). With Sacrifice, which was an RTS/RPG hybrid where wizards led creatures against each other, you could have Jedi and Sith masters leading all manner of soldiers against each other yet still be able to lightsaber-duel and use Force powers.
