I won't say this or that is "op" but here are my thoughts on torpedoes and destroyers in general, both from playing them (and against them) in WoWs and Navyfield 1 & 2 for many years. All the following assume the player will be doing their utmost to fight and maneuver well to the best of their ability and that incoming fire against the destroyer is high explosive not armour piercing.
1.) Destroyers are incredibly fragile in WoWs, nearly every hit something falls off, breaks, or is set on fire.
2.) Destroyers are incredibly hard to hit in WoWs, with flight time of roughly 2-12 seconds it is very easy to make a slight course or speed adjustment and avoid incoming rounds.
3.) Destroyers seem to have a tiny hit box significantly smaller than the ship model with apparent "hits" going through the graphic of the ship but rather than an explosion you get a splash.
4.) Very stealthy, some how several thousand tonnes of metal with engines screaming, throwing out billowing smoke whilst charging at 35+ knots isn't often visible until 5-6km away when its fire starts landing at your and the torpedo warning is sounding
5.) Destroyers will then pop the smoke after completing maneuver 4.) as above and rather than it be a factor of injecting fuel into the exhaust stack to produce grey smoke over time behind the ship, i acts like a mile radius smoke grenade with instant effect.
6.) Add all of the above with a bit of border humping and say good bye to your CV
7.) In a pick up group session based pvp game where ships get EXP based on the damage they inflict on enemy ships it is no surprise that DD and CL do not want to baby sit CV and BB, there is simply no EXP to be had in that role unless a DD or CL is able to break through, which granted they can do with ease in most battles given that as stated most players are forced to be selfish to progress. But if it is a battle where the DD/CL/planes do not come then you will have a boring 10-15 minutes without profit.
8.) The point of 7.) monologue is that balancing destroyers and torpedoes is not a function of unrealistic expectations but on the fact that a DD with a torpedo reload of around 20 seconds is broken, battleships have nerfed accuracy with main guns AND a 30-35 second reload and RNG will quiet often bounce shells for little to no damage even with large HE shells, torpedoes are just point and spray with just a single hit doing such overwhelming and flooding. It is unfair for torpedoes to do "realistic" damage, whilst having a very unrealistic reload time.
Just my observations and thoughts for your review.
SC