I agree with Ramblin Wreck on removing one's own Luvdisc. It's similar to Facebook's "Unlike" feature, where you can only "Unlike" a thread that you have already "Liked." This is contrary to what many posters have suggested (not in this thread, surprisingly) about featuring a "thumbs down", which would make Smogon a more uncomfortable environment. An Unlike feature does not add a negative stigma to a thread, but merely removes your approval of said thread if and after it has gone overboard.
As for the stars system, I honestly remember very few threads that were actually given stars, and most of them were stickied anyways. Stars don't represent the community, but only the views of a few badged members who happen to give a shit about a thread. Luvdiscs, however, help bring us to a popular consensus on what we, as a community, think are quality threads. Of course, as with any system that requires a mouse-click, this can be abused, but is it really difficult to distinguish between a crappy thread with 10 Luvdiscs and an awesome thread like Fatecrashers' Art of Fate that has a gold Luvdisc?