I found a lot of the Jadzia/Worf romance almost unwatchable.
(Gentle nudge back on topic)
And Ezri/Worf was a little more bearable? Talk about making an awkward situation worse.
Worf brought the Klingon side of the Dumbinion War to us, the viewer. It's possible that another Klingon character could have set the same stage, but a familiar character made it easier for us, the armchair quarterbacks, to accept. It would have taken several awkward Ezri-esque epiodes to introduce a new central Klingon character, and the only difference would be that we'd be bitching about that instead.