KOTOR was a much better game series, however the things that made it a better series of games are things that the casual market doesn't care much for, so Mass Effect is liable to lead most polls on the subject due to the massive lightening of the RPG elements.
Mass Effect was stated to be the spiritual successor of KoTOR. It's important to understand that the thing with Mass Effect is that it's their own IP. KOTOR was dependant on not one, but TWO liscences. One was of course "Star Wars", and the other was the D20 rules owned by "Wizards Of The Coast". I think people underestimate how difficult it is to come up with a set of functional RPG mechanics that work well with a computer game, the D&D/AD&D/D20 rules have the distinction of being one of the systems that does, and that made it relatively easy to make games using those mechanics... especiall seeing as WoTC's own Star Wars liscence meant that a lot of the work in statting things out was already done, and just needed to be tweaked a bit.
Also, "Old Republic Online" has doubtlessly influanced them wanting to move away from single player RPGs based on Star Wars. Competing with yourself is rarely a good thing, and you'll notice you saw something very similar happen with "Ultima Online" where it was pretty much the death knell for the development of further single player Ultima games, despite the brief attempt with "Ascension".
Mass Effect was stated to be the spiritual successor of KoTOR. It's important to understand that the thing with Mass Effect is that it's their own IP. KOTOR was dependant on not one, but TWO liscences. One was of course "Star Wars", and the other was the D20 rules owned by "Wizards Of The Coast". I think people underestimate how difficult it is to come up with a set of functional RPG mechanics that work well with a computer game, the D&D/AD&D/D20 rules have the distinction of being one of the systems that does, and that made it relatively easy to make games using those mechanics... especiall seeing as WoTC's own Star Wars liscence meant that a lot of the work in statting things out was already done, and just needed to be tweaked a bit.
Also, "Old Republic Online" has doubtlessly influanced them wanting to move away from single player RPGs based on Star Wars. Competing with yourself is rarely a good thing, and you'll notice you saw something very similar happen with "Ultima Online" where it was pretty much the death knell for the development of further single player Ultima games, despite the brief attempt with "Ascension".