Thats some super nice ideas!
I also always liked the idea to not have hundreds of units at the same time. (The opposite to Supreme Commander & co). I really like to give every unit value. Like rather heal a unit than creating a new one. Maybe we need an rts where you're not that big super powerful empire but rather a tribe or a village fighting against others (like the settlers).
User Interface is one of the top priorities, as you said! The UI in AoE2 just feels right with super intuitive shortcuts, just the right amount of info and satisfiing interactions.
The RTS i would wish for would not be as stressfull as AoE or Starcraft. Clicks per Minute should not take the topmost priority. Thats not what i would want to play.
Thank you for your input and feel free to come back if you have any of those great ideas! I'm still trying to get to know what people actually want in a rts game.