I remember in an issue of Starlog
at time of Ghostbusters II Murrary said he wanted it be called "The Last of the Ghostbusters".
I always assumed it was his desire to limit endless sequels. Perhaps an early pitch to him was a true ending to their adventures.
I am also a fan of the most recent Indiana Jones. At least there was a strong desire of all the prinicpals to return. While this whole thing reeks of a cynical money grab.
Another problem is I don't think Ghostbusters ever properly established itself as a franchise. The second film owed too much of its plot and characters to the first one. So now there is an expectation of seeing Louis and Dana again. With Indiana Jones, you just put him into a new adventure. Its hard to imagine that Peter, Ray, Egon, and Winston have been living in that same Firehouse busting ghosts for over 25 years. The second film already did the "lets bring the gang back together" plot.