Then again, it's a shitty idea that's never worked, so thankfully never used in a franchise we like
I'm somewhat inclined to say that you're comparing apples to oranges, though.
Let's look at
Star Trek. By the time of "Encounter at Farpoint,"
Star Trek had three television seasons and four (soon to be five) movies under its belt. It was a proven long-distance runner in multiple formats. After the success of
The Next Generation, it was natural to have "passing the torch" scenes in "The Emissary," "Caretaker," et al. It had been proven that the concept of
Star Trek -- some folks explore the stars and see a bunch of weird shit along the way -- could work in various permutations, and the tradition of having a cast member from the previous series "launch" the new one just became a nice way of starting again. Nimoy in the 2009
Star Trek was used in a similar way, primarily to give legitimacy to the reboot.
Ghostbusters, though, is not a sci-fi / action piece, which a lot of people seem to be forgetting nowadays. It's a buddy comedy with supernatural elements used to generate much of the humor. That's why it worked: Two dorks, a smart-ass and a token black guy were thrust into saving the world.
Ghostbusters worked
once, and that was back in 1984. The sequel was mediocre, the video game was decent for what it was and the animated series was hit-and-miss (and, really, an entirely different beast), but the magic in the idea has only been found once, and that was on the first try. The guys who put the idea together in the first place, Aykroyd, Ramis and Reitman, failed in their second attempt. I'm hard-pressed, in fact, to think of comedies that
have worked well as franchises.
It just strikes me as incredibly premature to say, "Of course it can work! Look at
Star Trek," when they're two entirely different properties with entirely different histories.