Agree whole heartedly here.

Events could come in the form of world wide like the horde of barbarians to individual units.

Unit types events.  Finding a new weapon.  Getting a level of xp

Soverign events...getting a researched spell quicker, finding or losing a spellbook

City events.  Spy took out a building, have to rebuild, get building built faster.  Find new techs that open up new buildings.

World changing events.  Volcano appears randomly on map, spawn points are added as monsters now are more powerful, Launches quest event that any group can tackle for a benefit.

There is a ton that could be done with this.