Besides, there's also a bit of a continuity problem here. In all previous wars that involved the Federation--or any other race, for that matter--we saw fleet sizes of a few dozen or more being interpreted as pretty damn impressive. The joint Romulan-Cardassian fleet, for example, was interpreted as a huge Armada, as was the fleet at Wolf-359. The Klingons with their extremely numerous Bird of Prey fleet surrounded DS9 with "Dozens" of warships in Way of the Warrior, and then combined with DS9's defenses it was still enough for them to be driven off by a force of six starships. Then all of a sudden we start seeing fleet sizes of a hundred or two hundred at a time... even for a wartime footing this strikes me as unusual.
So I imagine fighters are pushed into service as a stopgap, probably until more Defiant class ships could be built and fielded.