The first thing I want to do for Elemental is make a mod adding a new coalition of races called the "Fae". Though I expect races to become big after launch with mods, there is no room for it designed right now.
Examples:

Civ selector. What race are you playing when you select a civilization? All it says is you're choosing between Kingdoms and Empires, what does that mean? Shouldn't I know that I'm choosing between Humans and Fallen (And other mod races) and between life magic and death magic? What are the racial advantages and disadvantages of my choice?

Same thing again when selecting opponents. Shouldn't I know there are very important differences between opposing factions? Can different races like Fallen and Humans even interbreed with the dynasty menu? Let alone when I add a different race of life magic users?

Wouldn't it be interesting to know the unit differences between men and fallen? What about if I added in new races with new abilities? Notice that if I develop "attack dogs" as a unit, I've got no place to select them. When I develop my "Fae" mod I want to be able to select producing units of different races. Because I'm not going to outfit them the same. It works the same with people as well as my ballista operators shouldn't be wearing full plate and wielding halberds because they wouldn't be able to operate a ballista doing that. Need some kind of "basic" unit type selection here.
These are some things I'd like to see made a little easier to mod right now. If other things come up I'll be sure to note them.