I disagree as far as it concerns having to change up your fleet just to fight them if you found something that works and have been using so far up to the particular point in the playthrough.
Not sure how that's a legitimate criticism. If an opponent is harder, then pretty much by definition it means that a fleet which could defeat all opponents up to that point may or may not be able to defeat it. So you may have to improve your fleet to defeat it.
That's what being harder means. Most games nowadays are designed specifically for the player character (in Starsector, the fleet and officers more generally) to gradually improve through in-game tasks such as fighting -- you are
not meant to fight the endgame boss with your starting rusty dagger.
I don't know if you're trying to say that you think a fleet that can just handle mundane faction fleets should be able to waltz into red warning beacon systems and smash through full Ordos fleets. This does not make sense, since, as mentioned previously, Ordos are endgame, faction fleets are not.
You have already invested 10-ish hours just to get to that point, to turn around and tell the player they need to dump the fleet they have been playing with so far and pick up a specialized fleet with specialized officers and with a new set of ships with s-mods just to fight remnant Ordo's is like a slap to the face really. Thats not to say Remnant's shouldn't be hard, but they are hard for the wrong reasons.
Again, I don't see this as a legitimate criticism. Your fleet is not permanent; you should be improving on your fleet (i.e. getting new ships and retiring old ones) over time. This is no different than getting new weapons and armor and retiring old ones in an RPG. And yes, in any RPG, you have to spend time doing so, you don't start off with an endgame-capable party, but you have to work toward it by playing the game.
For this game, if you understand how Ordos fleets work and principles for designing your fleet to defeat them, then you don't really have to dump your fleet much if at all; your fleet will just be gradually accumulating in power, able to handle tougher and tougher fights, until it's able to beat Ordos fleets, if you've planned around it from the start. If you never encountered Ordos fleets previously and thus have trouble defeating them with your current fleet, resulting in you having to dump your current fleet for a new one, well, that's just part of learning any game, figuring out how to defeat the endgame challenges, which may mean reworking your current character (i.e. fleet). In my current playthrough I don't think I've ever bothered to redo my skills, but I've planned around Ordos fleets from the start.
You only need a specialized fleet to the extent that it follows the general principles for beating Ordos fleets. This isn't about looking for a particular Sword of Dragonbane that you need to defeat the endgame Red Dragon. There are literally hundreds of different fleet configurations that you can use to defeat Ordos fleets. It just comes down to your understanding of how they work, and that's part of the fun of Starsector (and of any game, really, figuring out the endgame challenges).
Yes, you could spend the time and credits to produce a specialized fleet just for fighting remnant. Yes you could probably wheel out the Xenorphica just to burst down a station with a fleet of tanky cruisers as backup, but it feels like it goes against what starsector teaches you for the most part when you start out learning the game...
Fighting Remnants is optional. So you never have to build a fleet for it if you don't want to. But if you have a Remnant-capable fleet, it's not "just" for fighting Remnants; it'll be capable of handling nearly every other challenge in the game (with a couple of exceptions). That's a large part of what makes Remnant-capable fleets worthwhile, and once you learn how they work, it's not really that difficult to come up with different fleet compositions and strategies for handling single and double Ordos. (Triple Ordos takes more care, but is still plenty doable.)
Not sure what you mean by it going against what Starsector teaches you, Starsector does a pretty good job of exposing the player to the challenges that'll be faced for Ordos fleets, i.e. against fast hit-and run ships. This includes LP fleets, phase ships, Tri-Tachyon fleets, and so forth. The principles for beating them are largely similar.
I did go back and set the DP back to 200 however vs remnants. In hindsight, that was smart and battles are alot more manageable now to split time between commanding and fighting.
Yes, making the battle size smaller will make Remnant fights more manageable, and it's helpful for getting a handle on them and figuring out how they work. However, it's also a sign that your fleet could be improved, and a more capable fleet can smash through enemy ships faster with a larger battle size, so that you can go through fights more quickly thus saving you time. My current fleet consists of 155 DP's worth of ships (1 flagship Medusa, 5 Falcon XIV's, 22 LP Brawlers, with Support Doctrine), which implies a battle size of 260 to deploy it all (at 60% of battle size); however, if I set the battle size to 310 (so that the fleet is 50% of battle size instead), the fights finish around 10-15% faster because they don't have to sit there waiting for enemy ships to spawn in, but can more constantly be killing enemy ships. So smaller battle size isn't necessarily always the answer.