you can grow economically with Pirate Coves
Not really.
You can only place a pirate cove in factions you are at peace with every 10 turns (or was it even longer?). It's extremely expensive, too.
And upgrading it is even more expensive. You can easily spend 10k on a cove, money better spent on an army that is going out to raze and conquer.
It would take an eternity for that cove to start paying for itself - and even then, that only happens in case that settlement isn't razed or destroyed by anyone. If that does happen (and it happened to me in over 70% of my coves), your entire investment is lost.
So it is a high-cost and high-risk investment, that has a way too long cooldown.
You can place pirate coves in settlements you are at war with, of course, and for free, too - but why would you ever do that vs just grabbing the entire settlement?
Since you are at war with the faction, they are a threat to you and you'll destroy them, anyway - so eventually your cove would get lost anyway.
There is no good reason to place a cove after winning a settlement fight. It's like choosing between getting all profit from a settlement vs just a bit (and that bit can easily be lost again).
In addition to all that, coves do not show up in your list of owned settlements so managing them is a finicky nightmare.
In the end, there really is no point in pirate coves vs just conquering everything.
About the Vampire Coast gameplay:
Their biggest problem is that they are a one-trick pony. Most factions allow you to play them in a variety of ways.
But Vampire Coast's only playstyle is tons of artillery + ranged behind chaff. Maybe Cylostra with a banshee + mournghoul army would be the only alternative.
Their artillery and ranged is quite good, yes.
But all of their other units are honestly pretty bad. Depth Guard was nerfed into the ground from a good tank+DPS to a barely usable DPS, which is terrible given their high tier.
Deck droppers are useless against ranged factions - which is funny given you'll mostly be fighting elves.
There's no cavalry.
It is a big problem to get your ranged infantry to actually shoot at the enemy if they don't happen to be on a hill or your frontline is crabs. There are better frontline units than crabs, but since they are spread out so far, they allow gunfire units behind them to actually do something.
Basically, Skaven can do everything VC can do - except better.
On a positive note - I don't think there's a more satisfying unit than Queen Bess. And no more satisfying spell than the Vangheist's Revenge. And the meme potential of bloated corpses is insane - at least in campaign.
I also found them fun to play, but I don't think I'll do another campaign with the pirates. Maybe with SFO.
CA really wasted some opportunity with them.