NUQAR'S Kentucky "Nuqar" James XXL 说:
That has very little to do with stamina and much more to do with formations breaking up if they charge for more than a few metres.
No, it actually did have to do with "stamina":
"Chlapowski writes: We could see confusion breaking out in the Spanish army. They tried only one charge. Some regiment which looked like black hussars, which I had never seen before, drew particular attention to themselves. Their attack failed, and was doomed from the start as they had begun to gallop at 1,000 paces and so were exhausted by the time they had covered half this distance."
"Experience has shown that the best distance from the enemy to begin the gallop, is between 200 and 50 paces. This gradual increase of speed is very important, to prevent the horses from being completely blown on reaching the enemy."
Cavalry Tactics and Combat during the Napoleonic Wars
That's not to say that inability to keep formation for too long when galloping wasn't problem as well.
NUQAR'S Kentucky "Nuqar" James XXL 说:
You could probably do something like this in bannerlord, but it would require you to have tight cavalry formations that can only do real damage if they all arrive at once, unlike in warband where even a single horseman can smash into infantry and feel no compulsion to get the hell out of there.
It would require combat to be more tactical and more realistic, with much bigger emphasis on formations. Battles were not series of duels between individual soldiers, they were fights between formations of men and those are two very different things. In MB battles are series of duels between individual soldiers and even if they are nominally in the formation they still act as individual duelists rather then part of the formation. Which is why things like stamina doesn't combine well with MB combat.
Which is to large extend true also for you next point about morale:
NUQAR'S Kentucky "Nuqar" James XXL 说:
What I would much prefer is a good morale system since that doesn't reward the player for camping or doing nothing. If your men keep winning their fights I see no reason why the game should force them to get debuffed, while I definitely think this should be the case if you let your men get flanked or charge them into unwinnable fights.
Problem here is again, that when men fight in a formation, formation have morale of it's own which is more then just plain sum of morale of individual soldiers of that formation. It's a situation similar to an animals in the herd. When in herd, individual animals acts differently then when alone. They act in a ways that may be irrational from the purely individual point of view. Moreover human "herds" such a battle formations also had commanders and they too had morale which played a role. Confident experienced commander would have been able to keep even inexperienced men in combat longer then incompetent and hesitant could experienced men.
MB combat is very arcadish and with little realism or resemblance of real combat. It doesn't have layers of complexity that would allow for implementing things like stamina in a way that would give results we might expect from it.
Unfortunately making MB combat less arcadish and more realistic would probably not meet with positive reaction from lot of players, because battles would become less bloody and less dynamic and less frantic. It would became impossible to play battles by mindlessly hacking, slashing and running over everything in player's path. And for most players that's exactly what they expect.
I for one am all for adding more realism in to the MB, but it have to be done systematically and with corresponding work on the AI. So in this case less is more. Let's first teach MB to actually start fighting in formations and use some simple tactic. Or to finally start using their polearms for goodness sake. After all due to difficulties in communication, tactics of ancient battles wasn't that complex. Simply because lack of communication did not allow commanders to execute complex manures so keeping things simple would in this case be also realistic (left wing, right wing, center, attack, defend, withdraw, etc...). Then we can see if we can add things like stamina in to the mix.