I understand less aggressiveness might be needed, but it doesn't feel fair. You need to make sure there isn't any of the Storm Dragon sleeping peacefully right next to AI-players' cities situations.
Would it not be better to also thin out monsters near the AIs' starting positions?
Actually monsters being less aggressive to AI isn't a problem.
Strong+ (and stronger) Monsters who start randomly wandering the map and attacking player cities before turn 60 or so because the AI pissed them off by placing a settlements/outposts is the issue.
I don't mind the monsters wandering or even attacking my moving armies or improvements that just adds to the fun... its the cities that are the issue.
My current game on normal Diff, Tarth (i think) put an outpost in the middle of about 6 monster lairs about 5 squares outside my border to get at a wilderness shard. several of the monsters (including a Strong/Deadly Elemental led Army) is now stampeding through my core cities. This is early game still around turn 50 or so... my Sov and champion are still under level 10 and I'm currently starving off the inevitable with "tremble" hoping I can recuit research Beorn's letters and get a third high level champion before i run out of mana. There's a wolf pack that for some odd reason I can't defeat wandering around as well causing issues.
(I already tried massing spears in the cities to defend but that didn't work out very well. (just got clobbered... I'm working off an earlier save at the moment. and the issue repeated itself almost exactly.)
p.s. while I was concentrating spears in the nearest city at threat I had a bear wander through and destroy a level 2 city. that just seem wrong to me.