Yeah, I was unhappy with what DRG did with Sisko and still largely am but my favorite real life heroes had very flawed personal lives. We have to accept they are human and sometimes they screw up and other times they are put in situations where no choice will make everyone happy, even the protagonist. Though I was angry with DRG, I've come to accept his route and anticipate what he will do next. Though Rough Beasts angered me when I read it, I can't deny that it was a good book with great characters.
As for DS9 itself, I think the "DS9" saga is over and I say that as a HUGE DS9 fan. The Cardassians and Dominion are no longer a threat, Bajor is a UFP member world, and the main characters have mostly moved on in their careers/lives as you would expect. How many serve in one place their entire career. DS9 had a story to tell, and it did it well but Unity really concluded it. That said, the franchise can still tell great stories that involve DS9 and its main characters. I like what Mack and DRG did in the Typhon Pact by using DS9 characters, continuing their stories but not telling DS9 stories.
And though I would love more O'Brien; I feel he has had a hard life; let him have his rest and family time on Earth free of risking his life. He's earned it. My fictional heroes deserve their rest and retirement even as my real ones do.