KOTOR is certainly a great starting bridge between JRPGs and WRPGs. It's intriguing to note how many trappings of JRPGs the two games possess, while intertwined with the dialogue choices and the player's ability to choose and manipulate how certain events transpire.
Plus it's worth playing the games just for the characters and the conversations you have with them. You have the psychopathic droid HK-47 who would have made any of the Star Wars films infinitely more entertaining, up to the enigmatic Kreia who delivers some astoundingly thought-provoking lectures to you while berating and belittling you if you commit certain actions that go against her ideals.
Mass Effect, though a series I adore despite a series of misgivings (*ahem* Kai Leng and the ending come to mind), is understandably not quite the spiritual successor to KOTOR that many would have wanted to warrant the significant, unanswered demands for a third KOTOR. Sometimes it's fun to just be as cartoonishly black-and-white evil as you can while swinging red lightsabers, especially for fans of the Star Wars licence. Obviously Mass Effect doesn't grant you that black-and-whiteness (though incidentally KOTOR 2 thematically challenges Star War's innate black-and-white dichotomy anyway) when it comes to dialogue choices and how to influence events. Shepard isn't going to actively pursue the path of villainy, and it's up to the player to determine the methods he goes about to be a hero in the end.
Plus they really don't play alike. KOTOR has this pseudo-turn based combat system that would suit first-time players venturing outside of the JRPG fold. Mass Effect turned increasingly more TPS/action-oriented as time passed. I think there's certainly room in the world for both KOTOR and Mass Effect to be successful, buuuuuut you know, EA. God knows what EA would do with KOTOR in this day and age anyway. I suppose at the very least EA would have given us a complete version of KOTOR 2, albeit with DLC.