The current state of the game can be summarized by the following: the lead designer had an in itself interesting idea (make Civ5 1 upt, because Panzer General is cool) and at all costs that idea was implemented. Maybe he thought that changing core mechanics would be easy to balance. Well, it's not. Stacking non-combat units (a very sensible approach and for sure suggested by the beta team) apparently wasn't even an option; at all costs the holy 1 upt had to be implemented! So that lead to the boring, broken game now. I haven't found yet any experienced good Civilization player who states this is even remotely a good (or even fun!) game.
If you want to make 1 upt balanced and challenging you really need to totally rewrite the combat mechanics in Civ; all units need reworking (attack, defense, movement, bombardment, ZoC etc.), probably number of tiles in a map needs reworking and most of all, the AI needs a TON of work! Without all that you get, well, Civ5. Horsemen are now overpowered, but it's just the tip of the iceberg.