More useless? UEF can’t even properly push into a barracuda spamming player because their stealth makes it pretty much impossible for the coopers to take a good engagement. Barracudas have slightly less range but slightly more speed so they can pick off coopers and retreat. I couldn’t tell you much about vespers because nobody makes them since Exodus is insane. T3 subs don’t have a problem with coopers either.
To make UEF have a proper destro you need to then make cooper a noobtrap unit. As long as cooper exists, UEF destro needs terrible torps. If it has terrible torps, it can’t be uses as a destro because it can’t counter subs so it cannot compete with phim destro ever. That means Phim has both a better frig and destro. Likewise, barracudas will always snack on the destros meaning UEF has less destro mass (especially since you absolutely need shields for the terrible range of coopers) so a valiant needs to equate to 1.5 exodus or so in total value in this mix to be considered a “proper destro.”
Honestly I don’t even care if subs get an additional buff to compensate, I still want them to be the intel ship of navy rather than frigs, but T2 subs still have the usage of being frig spam killers and coopers are heavily punished by said frig spam. Coopers also die to destros in a few volleys. They also die to torps just as quickly as T2 subs while being infinitely easier to spot. With these adjustments, they’ll also be significantly slower than T2 subs so they can’t be proactive about responding to every sub going around raiding the map.