It would be nice if instead of completely destroying buildings, you could dismantle them which would allow you to recover individual raw materials, that's what I miss. The idea of plundering buildings is also interesting, as disappearing entire cities is hardly the way to go, and it's becoming a bit monotonous.
Unfortunately, the artificial intelligence, not only in this game, still often remains at a low level when it comes to competition. I can see that the problem of it building warships does not only affect me. I think it's probably an underdevelopment of something, rather than an unwillingness to navigate the seas and fight battles.
All in all, it is a pity that it is not possible to block precisely such players who systematically leave in order not to lose rank. This is probably a problem that not only affects you directly but also many other players (it would be nice if there was something to emphasise that we didn't run away, etc).