Tldr; destroyers are good 'infantry' style ships with nice offensively oriented stats, but have been left behind by the skill system, emergence of counters, and lack of elite ships.
So as a preface, I've used destroyers a lot, and they used to be my favorite ship type: my 'standard' progression would be to go straight from a destroyer group to a mixed destroyer + capital force with maybe some specialist cruisers like gryphons or herons, but otherwise I didn't consider basically any cruiser worth using instead of destroyers. I would still say they are my most used ship type for the majority of the game, but that's mainly because I don't spend all that long in what is considered 'endgame'
Destroyers:
- Have lots of firepower per DP. Destroyers pack more dissipation/guns/missiles/fighter bays, and offensive systems to back them up, than any other class save maybe capitals.
- Depends a bit on which ship, but have good defenses per DP. Sunders are an exception of course, but Enforcers are bricks, Medusas have great shields (and so do Shrikes actually, but they are def 'light' destroyers and the narrow arcs are a bit of an issue), and even the Hammerhead has a decent shield/armor combo. The issue is that, unlike firepower, these decent defenses can be isolated and overcome if a bigger ship jumps them...
- Are flexible in how they can be built. Going for shorter ranged, higher damage guns lets them quickly kill frigates (rather than just zone them out) and gang up to overwhelm larger ships, while using 'artillery' style builds (Grav/Ion/HIL sunder, HVD/Mauler Hammerhead etc) lets them hang out next to larger ships and still have the range to hit other large ships (1200 range HVD is longer ranged than 800 base range cruisers (1120 post ITU) and near 900 base cruisers (1260). A 1400 range sunder is fighting at cap ship ranges.). I think that these artillery style ships are somewhat unique to destroyers.
- Have a good balance of range and speed vs nearly every ship... except those that have come out recently. There have been a lot of ships perfectly suited to hunting destroyers that have come in the last few updates. All of the fast cruisers and capitals that have burst mobility systems to get in range, negating the fact that destroyers have good defenses per DP by momentarily isolating the destroyers to pummel just one. Destroyers used to be fast enough to run from things they couldn't kill, but then a whole lot of destroyer hunters showed up!
- There are no elite destroyers (save the Harbinger) and no specialist destroyers either (save condor/drover, but those are simply outclassed by the Heron). This is contrasted with frigates where a lot of the useful endgame ships are either specialists (omen for disabling/zone anti-missile, monitor for disabling the enemy AI) or elite (LP Brawler, tempest, hyperion, scarab, afflictor, etc). Destroyers are in the same performance category as lashers and wolves: decent ships that are a big step up over converted civilian ships, but worse than the elite ships.
- Officers are limited, and it can be hard to justify putting one on a destroyer in the endgame. Not when elite frigates exist who give more ECCM, more Nav bonus, more damage boost from wolfpack, all while being a similar DP and more survivable vs mobility based offense.
If going for analogies as to what destroyers would look like if they were similar to the elite frigates people use endgame:
A 12 DP destroyer with a .6 shield, 130 speed, and 4 built in ion beams that fire over friendly ships and consume negligible flux. A single medium missile and 1 medium energy, 3 small energies. (omen analog tooled to more ship disabling rather than anti-missile/fighter)
A 12 DP fortress shield ship with enhanced flux stats and armor. I'm not even going to type more about this, it's making me want to throw up.
A 16 DP midline ship with 130 speed, two built in sarissa wings, 2 small missiles, 4 medium ballistics or combo of ballistics to similar weight. Ship system does something cool to the fighters (maybe breaks the rules of sarissa and send them to orbit the enemy ship plinking away?).
A 16 DP low tech ship with damper field instead of shields, 3 medium missile mounts, 1250 armor, and a giant pile of small kinetic mounts (maybe a few medium kinetics too). Very similar to an eradicator with permanently no shields, only meaner and cheaper.
A ship with a system as powerful as the time dilator on a scarab at 16 DP.
A 30 DP teleporting mini-radiant that for some reason is classified as a destroyer.
A hammerhead that got free SO and is 12 DP instead of 10 DP. Except that it already had accelerated ammo feeder, so how about it gets... ultra ammo feeder that does even more damage? LP Brawler analog.
Ok I got less creative towards the end there. But the point is that none of those ships exist. Some of them are similar to the fast cruisers that have come out and basically taken those roles.
Skills are also not good for destroyers. Despite the elite frigates being in the same power band as destroyers, officers in them get better damage bonuses against more ships (20% vs destroyers+ instead of 10% vs cruisers+), give more fleet wide bonuses to ECM/Nav, and they take less damage from target analysis. The wolfpack in particular is VERY painful because it kneecaps desire to put officers in destroyers (ECM rides on the officer too, but its a more minor issue). If I'm going to be putting an officer on a 10 DP ship... why not put it on an 8DP ship that will get larger bonuses and benefits more? Some of the best frigates also have
great ship systems that ramp up with a system expertise officer: omen, afflictor, and scarab (especially scarab!) all come to mind. Destroyers have overall nice systems, but possibly with the exception of the Medusa none get so large a bonus as the frigates. (Side note: Omens get more range from system expertise, in addition to activating it more frequently. It is... effective.)
Fuel is a big strike against destroyers compared to elite frigates AND cruisers. For frigates, it is 1 f/ly for 6/8 DP compared to 2 f/ly for 9-12 DP (and enforcer at 3 f/ly. Poor enforcer); 2/3 the fuel consumption of the 3 fuel cruisers (eagle, heron, gryphon) despite being 1/2 the DP, so overall 1/3 less efficient per DP. The Dominator, a heavy cruiser in the "fuel guzzler" family, has the same fuel/DP as a Hammherhead, and is nearly TWICE as fuel efficient as enforcers (5 f/ly for 25 dp vs 9 f/ly for 27 DP (3 enforcers)).
Support Doctrine on the other hand is really nice for destroyers: solid bonuses across the board, and the damage control in particular is really good for them as compared to frigates, as they have a lot more hull. I still use destroyers with SD in endgame, and have a good time, but I wish there was more use cases.
So, in terms of solutions: I would get rid of a lot of the 'scaling per ship class' modifiers in skills. They would work if the ship classes were distinct, but frigates slam right into destroyers in power. Maybe make them frigates and destroyers as one joint category, then cruisers, then capitals? I'm not sure what to do about the prevalence of destroyer-hunters. Those ships are fun to fight against, and its not really their fault that they are perfect counters for high offense/low defense ships of a smaller class.