Perhaps because the end of DS9 really didn't leave too many doors open. The Dominion war was over, and Sisko was off hanging the wormhole aliens. Odo left commune with his people, possibly for a long time.

Worf was supposedly going to the Klingon homeworld, but somehow always ends up back on the good ship Enterprise. ;)

Wasn't O'Brien going back to Earth?

Garak was going to stay on Cardassia and help rebuild.

Rom was going to become Grand Nagus, with Leeta at his side, and Nog would likely go where Starfleet wanted to send him.

That just leaves Kira, Bashir, Jake, Quark, Ezri, and Morn, who should have finally spoke and uttered the last word of the series.