The 30 ship limit always seemed like an arbitrary thing that's gonna go away once... whatever's meant to replace it comes into play. I dunno.
It replaced 0.6 style Logistics, which affected your fleet size (which varied by ship size) and how much personnel you could bring. Unskilled, you did not have enough Logistics to support a single capital (other than Conquest, which was bad at the time). At max Leadership/Fleet Logistics, you had enough to support three or four capitals (only), thirty or forty-something frigates, or some combination in between. You could exceed Logistics but took penalties, and if you took too much, you get accidents. For those who did not take Leadership, they needed overpowered Combat (and Technology) to solo entire fleets with a small ship because supporting a viable fleet (or even a lone capital ship) was not an option.
0.7 introduced fleet cap, which was 25. Problem? Fighters counted as ships, and the limit only applied to the player. Endgame NPC fleets regularly broke the cap, often having a ten to fifteen ship advantage over your fleet (or twenty or more if you left vacancies for captured ships). On the other hand, (I think) there were only core worlds, so player did not need Prometheus just to function (although it was occasionally useful to exploit fuel shortage before trade broke).
If player does not need to travel to fringe worlds, then 30 ship limit is okay. Although it would be nice if after battle displayed all ships that could be captured instead of only enough to max your fleet. (Makes that one perk that increases capture chance worthless.) At 30 ships, player can match enemy fleets provided he is not forced to dedicate too many to haulers and does not leave many vacancies for captured ships. Unfortunately, player raiding fringe worlds needs Atlas and Prometheus to carry enough fuel and supplies to maintain ships, and have capacity to carry loot.
Since my primary way of acquiring new ships is capturing them from the enemy or salvaging them from debris fields, I try not to let my fleet exceed twenty ships, so I have plenty of space for more ships. Thus, I often have a slight numbers disadvantage against the enemy. (I frequently use captured ships to auto-resolve pursuits. They probably do not have the weapons I want on them, just the junk I looted from previous battles.)
Well, frigate fleets are absolutely dead now due to 10 officer limit (unless you set ridiculously low battlesize). And I don't think it's a particularly good thing either.
If this was 0.7, I would agree. However, skills have been weakened enough that officers are not too much stronger than ships without them.
However, I think frigate swarms may be dead because of the AI's 0.8 era cowardice. If the enemy has enough ships to prevent yours from swarming them (and vice-versa), they all dance like Spathi until CR is at zero and then they taunt you like Monty Python's dismembered black knight by floating around on the screen like Oolite's trumbles. Frigates have low peak performance and are devastated by stalling. Not to mention that fighters eat frigates up like popcorn (which is a reason why my fleet has a lot of fighters).
The main reason to bring a big fleet is to have replacements. With a big enough fleet, it is not possible to deploy everything thanks to size limits, even if maxed at 500 (max should be higher than this). The extra ships are handy when player is forced to chain-battle. I cannot use Paragon for everything. Sometimes, I deploy the Legion, or Heron, or Hyperion, so that my Paragon is handy when I need it.