I'm with the OP when I say that I very much liked the concept. Hit the high seas, feel the wind in your hair and face, down a bottle of 12 with friends and just have a blast. Hearing about the scoring system made me think of WoW Mythic runs (timed duties with semi-adjustable difficulty). My fears, with this, were that it'd degenerate into a frenzied rush for max score within the given time. I'm sad to see that's the whole thing has boiled down to exactly that.
I noticed that people don't use /sit. No one. For the first time since starting out fishing, and having caught tens of thousands of fish myself, I now realize that the animations for standing up and sitting back down are 'wasted time' until the next cast. "So that's why all these people stay standing". I died a little inside.
Having finished my second run just tonight, I thought I did kinda okay! I listened to some advice to use certain baits in certain locations and doubled my score of last time. 'Nice', was all I could think. But not my friends. I heard one cuss that he missed a cast at the end and could've gotten an even higher score. Furthermore, I noticed this 'party score' button at the score list at the end... and found myself at the bottom. Now I didn't really care for the scoring, but I did feel bad about having the lowest score, because I thought that affected everyone's score.
And here lies my biggest qualm with ocean fishing. It's not the relaxing, sea-faring adventure I had hoped it would be, but has degenerated into some score-slogging party effort that I feel may be prone to harassment if you don't 'perform'.
For improvements, I need but refer to the 'of Dragons Deep' questline. That moment when I captured that Nepto Dragon, now that is great inspiration for this content. I'd feel far more thrilled and excited by that heart-beat sound & screen 'flash' animation whilst in the dead of a storm to have one shot at an elusive big fish than I do from seeing a flashy rainbow effect with merry music in the background and some insignificant fancy-fish-extravaganza.
As for making it actually fun, how about adding a giant sea-monster at the conclusion of the duty where players get a duty action to throw all the fish they'd caught at the monster to slap it into submission. Add cross-hairs to toss it at strategic parts of the monster's body and have it recover if fish reach its mouth so it can eat the fish, rather than take damage from it. Rewards could include gathering scrips, scrip bait, possibly unique bait that helps to capture the big fish out in the open world, you name it.
It's just a thought that occurred to me, but something that might improve the overall experience and helps to keep the content relevant in the long run.