You know, you've convinced me, I think the canon saucer is fine actually.
One of the interesting quirks of the canon saucer design was that it was just small enough that you could convert it into a single nacelle design, and just big enough that you could make a decently functional ship with just the saucer section and a single nacelle.
So if it "sure does suck compared to what we could build, and it sure will get facerolled by D7s," making some gold plated super-expensive monster is a bad decision. We're going to be thinking about stopgaps and war-era expedient builds.
And the canon saucer is the one we know can do that, because we know the Saladin existed, and means we can get most of the armaments and defenses of a larger ship onto a smaller, cheaper one.
Like, the arguments that the canon Constitution will be woefully inadequate is an argument that we should be thinking about how to deal with the inevitable failure of our heavy cruiser and how we can salvage something out of it during the war.