Sadly by todays standard games don't release fully ready. But that doesn't mean they should follow this trend. I'm sure that they could have waited releasing this game if that meant the RTS battles would be better.
The RTS battles honestly need a full overhaul. It feels like it was made in the early 2000's.
Archers are indeed way to strong currently and the AI seems to know this. In my playthrough I'm currently fighting army's made up of 80% archers. Maybe this is because it is England that I'm fighting but still that is a ridiculous amount and in no way realistic