Again, a lot of shipbuilding capacity is going to be absorbed by the Excaliburs, older ships, and probably other stuff that falls below the level of abstraction for this quest. We should not assume that the Darwin is going to be occupying the bulk of our capacity, and I think it's unreasonable to assume that it is. It is specifically called out as a small, specialized ship.
1)We are told that Starfleet stops building non-combat ships once the war breaks out.
This is only our 2nd Warp 8 design. I dont think its unreasonable to suspect that its going to be pressed into some sort of combat service in a war where we lost 75% of the 4-ship Radiant-class, and where even the Archers got savaged.
2)You are mistaken.
This is the only use of small or specialized I can find in the last two updates, and it was specifically qualified:
The Lull said:
The second is a science vessel that can take thorough surveys of habitable worlds. While the Kea has plenty of facilities for general cartography and geological sciences, the biological side of that has been somewhat neglected. Several colonies have had to deal with novel pathogens or had to implement crude solutions to the activities of local flora and fauna that could have been prepared for more efficiently given forewarning. Cataloguing an entire biosphere is no small task, and a ship dedicated to that could go a long way towards making safe colonies before the first boot touches soil. Such a vessel would ideally be small and well-specialised.
Note the use of ideally as a qualifier, noting that Starfleet is well aware that may not be possible.
We are probably going to want to keep it at less than 80% of an Excalibur's mass, but even so the CONOPS so far appears to be somewhat more permissive in mass-volume and role than it might first appear.
If we want to cover first-response capabilities we should build a cheap generalist light cruiser next, not try to cover all our bases with a ship designed to fill a specific niche.
We have a limited number of ship design and prototype teams, and ship design takes time.
Even if for some reason we thought a cheap (for given definitions of cheap) generalist light cruiser was an additional project to pursue right now, we probably dont have the time and resource budget to devote to it.
Furthermore the Federation's fleet-sustainment capability is limited; it can sustain only so many additional warships, and only so many crews of the quality to staff those ships within its operating budget.
Multi-role capability is more or less one of those unspoken assumptions in Starfleet doctrine as far as I can tell.
And its worth remembering that the canon Federation threw Oberths into combat against the Borg.
Everything is a first-responder in the Starfleet paradigm, as long as its fast or close enough.
