While I agree that it looks like the damavik is missing slots, and that it might be a kind of underwhelming ship, the thinking behind it is kind of obvious:
Needs only 1 turret compared to 2+ for other frigates: Has most high slots free
Intended for use with 2+ ships (remote rep bonus): Fewer lows (worse solo tank), more utility highs (for remote reps).
So yeah, if you are trying to fly a damavik solo, it’s not so great because that’s not its intended use. The bonused remote reps are useless and you are missing the other slots.
If you simulate them as a spider tanking pair versus a pair of other frigates, they should compare quite well.
And they scale even better with numbers: the more you have, the more remote reps the primaried fleet member gets on them to keep them alive, whereas other small gangs without a logi don’t get any help when focused or, if they have logi, you know who to primary and they won’t get any remote reps from their fleet mate.
In a regular fleet, your DPS scales like N and your tanking stays at 1 (local repairs). If you have logi, then it’s N-n DPS (logi have little dps) and n (+1 maybe if you local rep + logi) for tanking. Damaviks scale like N for DPS and also N for tanking. So yeah, they start low and they’re bad at low N, but as you increase the N, they should surpass many other fleet compositions.
Trying to argue that it should get more slots to be better at low N will just make it a monster at high N. Obviously, CCP went with the “start underwhelming and buff if necessary” rather than “start OP and nerf”. That’s generally the right way to do things since it does not upset the meta and buffs are well received. Otherwise everyone starts flying damaviks and gets pissed off when the nerfs kick in. Unfortunately, CCP is kind of slow at doing adjustments and I am not sure if swapping a slot will help all that much, but it does make it an ok pvp ship (sram, web, prop), while further emphasizing the spider tank vs local tank.