I realize that the discussion has largely moved on from making capturables invulnerable to the viability of capturables in the base game, which I'm ill-equipped to contribute to (started 20 games, won 2, and I usually play with all exos on).
However, my approach is more from the mindset of
"the fewer clicks the better" (which
Aeson apparently said before me; I'll claim "great minds think alike"?).
From that standpoint, I do think this is worth considering beyond the M+C cost of the units:
Why do I not care about Starship M+C costs, but I do about Mark V and even Mark IV fleet ships? Durability. [...] If you are using fleet ships, they are going to die a lot (and if they don't, you didn't need them anyway).
I think this is a large part of my thought process on the matter: if I cannot rely upon the ability to rebuild units I've "won," from any resource, then they are no longer durable in the least.
I already have to bear in mind the relative strengths and weaknesses of the various units to use them effectively,
which requires a lot of mental and physical work (at a minimum checking / remembering the resulting N x N matrix at all times). I then have to choose
what additional units I bring into the game, based on the strengths and weaknesses above. Those choices should have a direct impact on my success, in and of themselves.
There exists simply too much data to effectively handle treating some fleet-level units (i.e., non-super-weapons) as durable and others as not. This means that if I'm playing the game "properly" (at the high level, and not necessarily "correctly" / "winningly"), then
I should not have to pay special consideration to whether my units should be allowed to die. My strategic choices should have durability behind them, because the game is built upon durable decisions and costs. Otherwise, M+C+E+K costs don't matter, defenses don't matter, extra measures such as gate raiding or capturing buffer worlds don't matter.
At the end of the day, I have to accept that the ability to build those ships may ( =>
will) be lost.
Put another way, I'd extend Keith's question:
2) In a game with no superweapons, are AdvFact/ASC/Fab structures, assuming they're reasonably defensible, worth capturing?
Taken with the above, "reasonably defensible" requires enough defense to
always prevent loss, which means that loss is unacceptable. Via correlation:
should a capturable require the same level of defense as a homeworld? Not just
can you provide that defense, but
should you be required to? Then,
how many capturables should you have to provide a homeworld-level defense for?
Anything less, and you are saying that the player cannot treat the resulting units as durable, and ain't nobody got time for that.