I agree that mount and blade is a very nice game but lacks combat tatics.
However, it would be very hard to make these tatics work. Beside what has been already discussed (the AI's omniscience), there are other problems that would make tatics harder to be placed in the game.
For example, you can't divide your troops in groups as you please; you can only divide them by their types (archers, cavalry and infantry). That way, it's not possible, for example, to have some soldiers to charge your enemy while two groups of archers rain death upon them from oposed sides of the battlefield and a part of your cavalry charge them from behind.
Even if you could do that, having your men positioned correctly would take so much time that most of the "bait" would be completely dead when you do it. Also, the troops being repositioned would very likely be seen while moving, even if the AI wasn't omniscient.
In the other hand, being able to position your troops before the battle starts would make the player (and NPCs with that ability) very overpower.
Other problem is that you can only make your troops stand in the position YOU ARE STADING. You cant send them to a specific position in the battlefield.
I have some suggestions that could make ambushes, baits and enviromental tatics more plausible:
In the world map:
-> A party skill called "hide" or "camouflage" that would make your party harder to see while in the woods or other terrains. It would also make the party look smaller (less members).
-> when being pursued by an enemy, have the option of "prepare for battle" in the camping menu. The party would stop walking until the pursuer reaches it. However, when the battle starts, the pursued party would have some seconds to position theirselves before the pursuer enters the battlefield.
-> Another option of action while camping: "set trap". The party would divide in smaller groups that would stand ground around a perimeter. Them, the player would be able to bait enemy parties into that perimeter, considering that the group with the player would be small and therefore atractive to bandits, looters and enemy lords. When that happens, all the groups of your party converge to the enemy and attack it.
In battles:
-> being able to send your troops to one position (like pointing and clicking the mouse over a hill).
-> being able to, before the battle starts, divide your party in groups, that would substitute the "calvalry, hear me", "archers, hear me" stuff. The result would be "group 1, hear me", "group 3, hear me". With that and the item above, you WOULD be able to do what i said in the beggining: have some soldiers to charge your enemy while two groups of archers rain death upon them from oposed sides of the battlefield and a part of your cavalry charge them from behind.
and, at last, one element that would make gameplay more fun but also add some tatics to it:
-> when joining a battle already in progress, the battle had to effectively
be in progress. I mean, when your party enter the battlefield, the combatants are
already engaging theirselves. Also, the player could be able to join the battle from the oposite side (in other words, to enter the battlefield from behind of your oponents).
Sorry for making a huge post in bad english. I hope you can read it until the end
