I think the entire system is actually my least favorite part of GC. I actually would re-do the whole combat engine from scratch.
I would never have made defenses "exhaustible" for example. I would have made it so it was always a damage reduction. Shields of 10? Then every energy weapon hit subtracts 10 from damage, every-time, the spill over on each shot, takes off HP (possibly, defense can have a max damage reduction of 90%).
Missiles would be short range, because at long range, countermeasures would be more effective, and missiles have limited fuel, so the longer you can see/predict a missile, the more likely you can out-maneuver it. Energy weapons would mostly be long range, but generally light damage. Kinetics would be long to short range, getting more accurate as you get closer/etc.
Smaller hulls would naturally have more evasion.
...and I wouldn't let player's dictate a role. Roles would be hull types, and those hull types would get certain traits/stats to compliment that role and I'd probably have less roles.
therefore, there would be a direct relationship between hulls/roles and what they target. It gives the player less freedom admittedly, but that actually forces you to make smarter decisions AHEAD OF TIME. Right now, I could design a ship, save two copies, one as Escort, one as Guardian, and upgrade a ship in the field for virtually no cost, on the fly, to change the role as neccessary. No one does that because it isn't even neccessary though lol.
Right now optimum strategy appears to be: Make a near-weaponless escort fleet with HP+Evasion bonuses if not, use proper defenses, and then fill in that fleet with carriers or weapon-only ships set to Captial.
Never bother with anything less than a Medium Hull, and get two engines on your fleets. You'll dance around the AI, who love small ships and tiny ships too much, and your "tanking" ships will rarely die, while your DPS ships don't need a single defense.
Its all weird and gamey to me.
I'd rather the hull/relationship of the ship be predefined to prevent some abuse. Want to set your missile only long range ship to support? Too bad you can't. Oh and didn't put any defenses on it, expecting everything to go after the Escorts? Nope won't work, its listed as a "Capital Ship" because of the hull type, and my bombers are set to "Bombers" which hunt them and ignore escorts/guardians/whatever.
Your escorts innately have faster tactical speed, good armor, and numerous smaller weapons to attack multiple fighters/etc. at a time, and innately know to stay close to capital ships and protect them from fighters.
I haven't played Ashes of the Singularity, but I know they are putting a lot of effort into making a grouped army become a single "meta unit" where the right units naturally do the right job. A more primitive version of this idea exists in Sins of a Solar Empire when you group ships as a "fleet". That should be the general behavior model for fleets in my opinion.
Just my opinion. Love GC obviously.