devtrackers.gg
I think I stopped caring about the AI quests after I reached level 30 or 40. I am now a little over 70 and accepting any AI quest it's become really futile. Destroying a couple of frigates and a gunboat feels like a joke; I don't even have time to switch my view to the specific location - they already got destroyed, especially if appearing near one of my harbors.
Also, the money reward is insignificant, but I guess it's related to the difficulty of the quest. Still, 20k or even 40k is nothing considering I've topped up my wallet making 4 million, though I really appreciated it when I was just starting up. Moreover, when items are proposed instead of money, these are also low-level items. I could be interested in some Legendary ones, but no AI offers that (or maybe extremely rarely).
It's not only about the destruction quests, but also about smuggling, picking items or delivering goods:
- smuggling is a breeze ever since I got my first airship
- picking an item and delivering it somewhere is really boring
- delivering 2t of something to some AI is not challenging at all
- providing citizens with solicited goods is also very easy, especially when local
However, I did notice an increase of item prices - so that works ok. 
So, maybe you could spice things up a little as the player advances in the game by increasing the difficulty of the quest and correlating that with the value of the reward. 