Is this a strong disincentive to excessive raiding? There would need to be more in terms of diplo penalties to address the raiding exploit.
Suppose 25% off the max defense for each raid. 4 raids = 0 defense, which means that (I would guess) unless you have a ship already at the haven there would be no way to save it from an attack. Even at 50% the haven would not survive for long.
There are lots of havens, but not that many research centers and no new ones are built. As research centers fall the research rate falls for that faction. If PP is trying to win via that factions victory it will have to do more of the research, thus lengthening the game. A key advantage PP has over the factions is the ability to mix/match the fruits of the faction research. The Pandas also gain from faction research.
There are lots of havens, but the value of them is not the same.
In my view the best havens are:
a) those which provide recruits
b) those we can get tech from
c) those we can get materials from
I find the tech from research and haven defenses insufficient for my play style, so I need to trade to get enough. The more of such havens that are lost the more precarious my position becomes. While there is the “only PP tech” strategy, I doubt that is a popular approach. The game has all these fancy things in it, so people want to use it all. Is the value of LOTA the additional new missions, or is it the weapons?
The best for b+c are the NJ ones that provide both. Losing those havens would be a significant loss.
Recruits are a big unknown. On Hero+ all those level 1 or 2 recruits have very little valuable. I want as many opportunities to get those highly valuable 4/5/6 level troops as possible.
Location matters as well. If I raid all the conveniently close havens which then get destroyed, now my ships have to go further to make the trades. If you have enough ships, ok then this isn’t a problem.
While I don’t raid except for ships, the other raids are part of the game so then the question is how to keep them in the game, but stop them from being an exploit. It’s not a complete solution, but it does add some strategy for a trivial bit of code.