@artanissss
I'm lucky enough to have taken part in a good many battles over the last few days, as I'm on summer break at the moment and I wanted to jump in and reply to your concerns.
Leaving aside your comments around the mechanics for a moment, the battles as a whole did get a lot easier as we gained experience - using kegs for instance, even one crew using a chest of sorrows on the skellie ships - I think pirates are beginning to try a variety of approaches and finding what works and actually having a bit of fun experimenting with it. I have to say I have very much enjoyed every single battle, including the betrayals and attacks from other pirates at the end when they've occurred.
There's definitely a difference between the cursed fleets, with the grog cannon balls feeling the most difficult/frustrating which seems to be offset by them only shooting into the upper deck of the galleon most times. It's been mentioned elsewhere that the stacking feels slightly op at the moment, but again, I think as time goes on and we adapt to different strategies we can compensate for this.
As to the magic element, I wonder if you've read the lore book or seen the recent 'extra' page for the lore book which outlines curses and can be found here -
https://www.seaofthieves.com/news/tales-from-so-t-cursed-sails
Mermaids, skeletons, cursed chests, the Devil's Shroud and the supernatural in the form of the Ferry of the Damned are all part and parcel of the world of Sea of Thieves already, so cursed cannonballs fit right in, in my opinion. Sea of Thieves has never intended to be a realistic pirate game, it's set in it's own fantastical world in parallel with the historical period of the early Golden Age which is how 'we' found ourselves there as pirates.
I think this also gives some leeway when we're talking about the unnatural movement of the skellie ships, in that they need not be governed by the natural laws of the world - if you're sporting cursed sails on your ship then it's not too far a jump to assume they're filled with a cursed wind as well.
We don't yet know what these cursed ships are going to look like after the event, and like yourself, I would want cursed cannonballs to be rare and very difficult to come by in game afterwards - a special encounter, if you will.
I'm sorry you're disappointed by the update or feel there are things lacking, but thanks for posting your thoughts around this.