I'll probably catch a lot of flak for it...
But honestly, if there was one character that DS9 could have existed entirely without, I'm sorry to say it... but it would be, in my humble opinion...
He was tolerable, for the most part, in TNG because he represented a thorn of anarchy in the side of the oft-smug, somewhat statuesque group of "perfect" humans. When he got his own share of shows, that one where his racism came to the surface (the one with the Romulans and the Klingons who were living together) showed a side of him that would present itself far too often in the future- at least in DS9.
He was an unnecessary addition in the first place, and the way DS9 portrayed him was as a spoiled, immature somewhat racist character. Shows like "Let He Who Is Without Sin" brought that gratingly to the surface and yet inexplicably the writers kept shoving Worf and Jadzia together.
I found it telling that the extent of his contribution to the society in Children of Time was a small group of caveman-like outsiders who refused to contribute positively in any way until they were pushed to do so.
DS9 did fine without him, and it could have continued to do so. "Perhaps they will have to adjust to me" is just a bad attitude.
Agreed. There was NO need to add Worf to the DS9 cast, and he was incredibly unsympathetic to me. He worked fine on TNG (though I seldom liked a "Worf episode" -- the one point we seem to disagree on slightly), but was shoehorned into DS9 just to provide, in Paramount's eyes, star power.
I found a lot of the Jadzia/Worf romance almost unwatchable.