I like the idea of random events, for generic repeatable events (ie, Storms at Sea, etc..)
I've never been much a fan of scripted historical events, ie, inevitable one-time events that neither side controls, but both sides roughly when/where/how are coming and are able to prepare for with ahistorical foresight.
I think a better alternative to scripted historical events is to make more "player controled options." Emamcipation in FoF is an example of a player controled option. Major historic Events such as "Legislative Assembly Dissolved" would be something that could be triggered by the player by pressing an option button somewhere (or playing a "card" amongst a set of option cards dealt to the players); certain options might not appear right away, others might have certain pre-requisites, some might lead to other options opening up, etc.
You could get very creative with such a system, with option trees and branches leading not only into historic paths but plausible alternate history paths as well.
I agree that random events like stormy seas are not an issue - in fact, weather in general is already modelled in the game, and certainly there have been times when snow or rain has caused me problems in terms of my planned strategic movement schedule. Weather is a"normal", and certainly not "ahistorical" random event.
I'm more concerned with random events that might have a profound effect on many months of planning, such as a plague that wipes out half your Army, or your best General catches the flu and croaks.
You are quite right about historical issues being - with the knowledge of hindsight - easily anticipated. The reason I used the Republic of Mainz example was to illustrate exactly that point. In that example, it required player (or conceivably, AI) action to cause the event - occupation of the city of Mainz within a certain specified timeframe, by Revolutionary French Army forces.
These are, in my view, the best types of events to include - ones that require player choice or action to cause. If it doesn't, then either leave it out, or let it happen as a matter of "flavor" but the event has no impact on game-play.