I agree that long range ships are better in general and that kiting the AI is often the most cost effective option. However it's not as simple as "long range ships > short range ships". I have used Mark IV Bomber Starships on 10/10 difficulty a couple of times and they were extremely effective at cleaning "not so well defended" AI planets. During big AI attacks and when I attacked the AI homeworlds they worked as cannon fodder as long as AI Fighters were out of range and they also did a lot of damage.
There are situations where you just can't run away and you will have to face the AI head on. Like when the AI sends waves and CPAs. When the AI ships get closer and closer to your command station you have nowhere to run so you have to stand and fight or you lose the command station. So in that case it doesn't matter that much if your ship has 50000 range or 5000 range. Sure ships with longer range tend to survive longer but when you're defending against an attack with your back against the wall it can be a good thing that your ships work as a cannon fodder to make your force fields last longer. And they're_ships_so they can be rebuilt pretty quickly. And since you're under attack you're getting a lot of salvage so rebuilding the ships shouldn't be a problem (in terms of having enough metal).
And you_can_have overwhelming odds on 10/10 difficulty level too even though it's not as easy.
But even on 10/10 diff you don't need to unlock every single mark level of every ship and starship level to achieve superiority in firepower. End game after you have unlocked enough defenses you're probably gonna wanna at least get Mark IV Bombers. Then possibly Mark IIs of other triangle ships and/or Mark II or Mark IV bonus ships and a few additional starships. Possibly Mark II Flagships unless you have Munitions Boosters as a bonus ship. A fleet like that supported by Engineers, Mobile Space Docks and Warheads is capable of taking out AI Homeworlds.
Without any support it can clean up any AI planet that hasn't been on alert for hours in-game time. Ion Cannons, OMDs and things like that need to handled by Raider Starships and Assault Transports or some teleporting/cloaked ships regardless of fleet composition. AI planets that have accumulated hundreds of guards can probably be handled too if you have unlocked additional Riot Starships as you can kite the AI around. If the planet has supply beachheading helps a lot too.
Against Special Forces, Reserves and Core worlds you will need Warheads regardless of how many ships you unlock (I don't know about Fallen Spire campaign).
So things aren't quite as black & white imo. I still agree that just having tons and tons of options (not that I'd think there is going to be in AIW2) isn't always good. Look at the bonus ships in AI War Classic. There are quite a few bad ships and I'd_never_pick so it's almost as if they didn't exist. Surely it feels satisfying to slaughter 40000 AI Autocannons but I'd never pick Autocannon myself as there are other ships that fill the same role but are way superior. Riot Starship's modules are quite balanced imo.
Shield Bearers are pretty much game breaking in AIs hands. First of all AI gets literally hundreds of them. And they and everyting they cover are immune to tractor beams so all the AI ships just fly next to your command stations and destroy it. Zenith Siege Engines
(Keith's mental file about Kahuna's grudge against ZSEs gets loaded into the working memory and the filter activates) I've complained about before and I shall again. Again AI gets hundreds and hundreds of them. That combined with their long range and their bonus damage against force fields - and everything under them - makes them a no go. I don't hate them just for the heck of it. I dislike them because they're too powerful imo. Can't say much about other ships in Ancient Shadows because ZSGs make me disable the whole expansion because it's "the only way to be sure" I don't get them in my game. Imo that's a problem. So problems like that can occur when a lot of content gets slapped in.
add & add & add until it's a mess
Thankfully the nerf/buff hammer was swung many times.
EDIT: Almost forgot to say. I think what Keith proposed in the first post sounds good. Also I think Mark levels would be better than "Cruiser", "Battleship" etc. They could be saved for the Spire.