To be fair... even letting the Dominion occupy DS9 "at all" was a giant risk in the realms of Trekdom. I remember the first time I watched a "Time to Stand" I just got shivers from Dukat giving the Captain's Log.
Sure it would've been great if it lasted longer, but... well they can be forgiven that at the time the fans wanted a payoff to that story arc. DS9 set the standard in Trek for that continuous story telling. Could it have been better? Sure... but it's what we got and it was great. I wish Enterprise had taken a page from the DS9 book.