What do any of those have to do with the presence or absence of Ezri Dax?
A couple of points:
1. Worf certainly wasn't choosing to save his wife on Utilitarian grounds and if saving Jadzia to create Ezri saved more lives in the long run (along with any future Daxes), it's irrelevant to the moral calculus.
2. Ezri actually was involved in a number of missions including trying to save Worf that put them on the Cardassian homeworld and making contact with Damar. Among her many activities we have:
A. Helping shut down the criminal syndicate her family was involved in.
B. The Oceans Eleven heist where Vic's life was saved (and he's described as a sentient being).
C. Solving the Vulcan serial killer plotline.
D. Whether or not she's a good counselor or not, she WAS the counselor that helped Garak solve his issues (and strangely I'd argue it's the fact she's a TERRIBLE counselor that actually results in him having his breakthrough as he cant use his genius against someone who is so emotionally vulnerable).
3. There's literally no way that Starfleet could beat the Dominion in military matters, no matter what advantage they had. The Federation won because the Prophets vaporized the Jem'Hadar fleet from the Dominion thanks to Sisko, the Romulans were tricked into fighting them to buy enough time for the S31 plague to kick in, and Odo negotiated an actual peace. Everything else was just theater. Even Damar's revolt didn't do much to actually effect the war's outcome.
The idea of one Cardassian infiltrator having the power to turn the tide of the war is ridiculous.