The Omega's are literal "Battle-Carriers" in function, where they're a hybrid between the two.
Some of it's "Battle-Ship functionality was compromised" for a small Carrier Air/Space wing.
It's not that great of a "Carrier" because it isn't a dedicated Carrier.
But the Omega-class isn't supposed to be a dedicated carrier, it's a dreadnought carrying its own defensive fighter screen. It's not for deploying fighter squadrons remotely for missions etc while it holds back outside of the engagement zone. The Babylon 5 production team officially designated it as a "destroyer", which JMS acknowledged was because he knew nothing about naval terminology and thought it sounded cool – in reality a destroyer would be a small, fast, manoeuvrable escort intended to work as part of a fleet, more like the White Star (or in, Star Trek, the Defiant).
The two rotating sections are designed to balance out the rotational mass, like propellers on a plane.
I'm aware. But the reason it has two relatively narrow opposed rotating sections instead of three, or four, or a cylindrical one, is because that's as structurally simple, and therefore robust, as a large rotating section can be.
You need roughly the right amount of mass for each one and proper angles.
The number of blades or sections can be "Whatever Number" you want as long as you balance it angularly and properly attach it to the central spinning shaft.
Design Rule #1) You won't be getting very far with 1-Blade/Section, you need at least 2-Blades/Sections or more.
Design Rule #2) The # of Blades/Sections you have must be equi-angular and as close to identical in mass as possible.
Design Rule #3) If you can have a Counter Balancing rotating mass on the same axis, even better. See Contra-Rotating propellers and their benefits
I know, I've done the maths

I do love that fan design, very awesome, would've been better with a full Cylinder for the habitat section
But why would it be better? Do you mean aesthetically? Then sure, maybe, but these ships aren't supposed to be aesthetically pleasing, they're supposed to be functional and utilitarian. (I do love the Asimov though. One of my favourite sci fi ship designs ever. It's just so... cuddly.)