I agree with (B), but not (A); the Keas were so useful as line anchors for two reasons: beefy shields, and great phaser coverage for swarm-swatting. So I kinda think swarm-swatting is this thing's job- if the formation can maneuver to engage the enemy cruisers without enemy light combatants nipping at their heels, because the Feddie's phaser envelope is an all-round-or-close-to zone of death for said raider types, then it's doing its job correctly.
It is a fair point to note that the Kea was useful for engaging swarms of BoPs in the last war, that seems to just be stated textually. However I think we've already overshot the optimal price point and capabilities for doing that.
Basically, because (it is a popular opinion that) double-digit percentage increase in ST and α doesn't actually translate to a double-digit percentage in how much work the class will get done over the course of its service life. Pushing it from- pulling some numbers out of my ass here- "peer opponent for two K'Tingas" to "peer opponent for three K'Tingas" is only worth more than getting 10% more ships built if you expect to get jumped by three K'Tingas more than 10% of the time.
(Or, conceivably, if you're actually expecting a lot of all-out wars and expect to actually need the damn thing to anchor fleet engagements against enemy capital fleets [as per its design role] frequently- and most of us, while recognizing that that is the requested role and we do need to be competent at it, don't expect the design to actually find itself anchoring major fleet engagements at all.)
Otherwise, having 10% more hulls will mean getting 10% more patrolling and 10% more science and 10% more emergency-response and 10% more diplomacy and 10% more pirate-hunting done over the course of the next century- and also increases the odds that the fleet will be large enough to be worth designing and implementing a refit for, when the Warp 9 core and the next-gen torpedoes and phasers and shields and nacelles are all available, and maybe even again with the Warp 9.5 core.
(Also, I kinda think "enough to beat current- and next-gen enemy heavy cruisers" really is enough, because there just...aren't any enemy battleships that we're aware of.)
It sorta depends how we're phrasing the question? If we rephrase that as "the ship will destroy three K'Tinga before it is destroyed" versus "the ship will destroy two K'Tinga before it's destroyed", then yeah, for a 10% cost increase that's a worthwhile trade-off on the face of it IMO. Like, it's also a made-up scenario purely for comparison with made-up numbers so then going down a rabbit hole of where a Federation might actually fight three K'Tinga at once once is sort of a red herring?
Large fleet actions where our capital ships might have to engage multiple other enemy ones was definitely a feature of the last war, and is the whole impetus for the Project. Equally, the ability to destroy X% more ships in aggregate also means you can destroy individual ships more quickly and reliably. Really the trade-off here is do we want basically a mother goose for our lighter cruisers, or a flagship which can both screen other cruisers *and* packs such a big punch that it will kill enemy capital ships. The latter is necessarily a much more expensive, specialised design, but not necessarily any less valid or useful of one.
As I've said previously, I'd personally have been quite happy designing the Kea Mk. II, but then we gave this design extremely expensive features which make sense for a flagship and no sense for something whose only job is to essentially sit still and get shot at. So I'd prefer we end up designing a good flagship, rather than a somewhat overpriced bodyguard for Mirandas (who individually outmass an
Excalibur and really don't need protecting like the Newton did) which has features it does not need.
But again like, this isn't really a vote for what ship we want because that's decided, it's just about what gets the best value out of the ship we
have. Unless we have a DeLoran and can get it up to 88mph, we can't make this an economical heavy cruiser.