Since 0.8a, AI has become much more cowardly, and it did not get much better in 0.9a. Modern AI is still much more cowardly than in 0.7.x releases and before. It will stall until heat (or CR) death if given the chance. In worst case scenario (like lone starter Apogee), player may need to waste much time cornering the enemy before being able to kill it. This is different that earlier releases when AI will charge to its death at your ship(s).
Map size. The problem with smaller map size is you cannot deploy as much, and the player's side spends more time chasing cowards (and forcing his AI cowards to likewise close in for the kill) and kill them before new ones get deployed in a trickle. Low map size makes fights take longer, probably long enough to run out of PPT. If player's fleet will run out of PPT, then his ships need to retreat or be stuck. (If both sides are stuck dead in space, you stalemate in an infinite battle, and you lose by being forced to reload to end the battle.) Multi-round combat encourages player to camp at his edge of the map so he can retreat as soon as PPT runs out. Due to time reasons, bigger map sizes are better because fights finish faster. PPT was set mostly during the 0.6x days, but fleets and fights have grown bigger (ten capitals today instead of three before), tougher, and weaker (offensive skills weakened more than defensive skills since 0.8a), and AI is more cowardly since 0.8a (wasting more time).
What can frigates do late game? Aside from few specialist ones like Afflictor, just die, either by being outgunned or simply running out of PPT. Frigates' golden age was 0.6.5a, where a horde of them led by Hyperion could fight anything, recover quickly, and tour around core worlds much faster than any other fleet. Of course, food runs from Tartaress to Askonia with about fifteen Atlas led by Hyperion was still the XP and cash cow of the release.
But their CR drains as well, so if that's to be the deciding factor, then the outcome is predetermined based on whose ship has a higher PPT and more CR. Might as well not have a fight at all in that case and just announce the result to the player.
This is a reason why I favor a cruiser and capital fleet, so I can win stall wars if it comes to that. If AI will play coward, I will make sure they lose that battle. Waiting for victory is annoying though.
Re: Progression.
While I like to pilot a godship, if all the player can do is be a low-level brute that a power can sic at others like a dog, then the player faction can only go so far. It is like early D&D fighters that do not get much more personal power after name level (just a few more hp). Their main late-game class feature is attracting (possibly free) followers to build up an army or run a keep. If an individual fighter cannot keep with a wizard, he can use the people granted by his class feature to do the work of a hundred or so men.
Yeah, but in D&D you can choose to play a wizard. In SS, a fighter with a bunch of followers is the only option. I think the game would be a lot richer and more interesting if it gave you the option to play as a wizard.
Well, being a wizard in Starsector means developer cheats, like giving yourself money, changing rep, giving yourself ships including normally unplayable ones like Radiant or Guardian, erasing enemy ships... or hijacking and piloting them yourself. Creating or blowing up worlds. Teleportation. Insert weird or spooky stuff. Basically playing god.
What I meant by early fighter is player progresses from personal power to world strategic power. One human is limited to so much, so the way for one human get more power than one human is to lead many humans to do what that one human wants, and not necessarily in a fight, but to build up an empire so you have a home, steady income, and maybe political power to do things like mess with other kingdoms or give quests (to clear rat and goblin infestation in the basement) to other low-level murderhobos to do your dirty work while you focus on what you want to do. Old fighters graduate from being fighters to rulers to shape the world. Other classes get followers too, but fighter had the most, maybe enough to run a keep or small city-state. Modern D&D has removed the ruler part from fighter's class features and just gave him even more hit powers and maybe few more relatively minor buffs that make him a better meathead or dog in a fight. (In other words, nothing to help solve problems when violence is not the answer, such as manpower to build a bridge or other structure.)
It would be nice if late-game Starsector has some ruler things to do instead of locking the player's fleet into meathead mode all game.