If they were a lot more aggressive, would they be more tempted by naval invasions? i mean, it's just a feeling, but the AI seems to like sending naval invasions against me more than the other bots... i mean... portugal invading England in the early stages of the game? thats ridiculous.
Maybe its more tempted to do it if it's scripted to be more aggressive towards someone that's overseas.

Then again, that's probably unhistorical again. Just another thought.