This could tie in with a suggestion I've been making for a long time: to allow women to lead siege defences, which they often did, and their upbringing made some attempts to prepare them for that role. Obviously not a direct combat role, but inspecting, planning, handling the economic aspects, organization, logistics, reinforcing the morale, keeping the discipline, making political decisions and general governance.
Enabling noble ladies to lead siege defences (generally, in their case, they'd have been chosen because of rank rather than ability, thus spouses, mothers, sisters, daughers, in some instances maybe cousins of the male ruler, NOT the female courtier with the highest Martial stat present) would free men up to lead armies.
Plus, now rulers would need to balance campaigning with producing an heir: either the king would have to make trips, or the queen would have to follow him on campaigns. If neither, then no heir. Some women did follow their husbands on campaigns — which does not mean walking around in armour with a sword girded on etc. but basically being around. For counsel, for company and for... producing heirs.
More dynasties would die out or be inherited by country cousins as a result, as it probably should be.
Regents would have some more meaning too. Just like on a pilgrimage, you should have a regent appointed when you leave the borders of the realm — well, not exactly when one OPM (one-province minor) crosses into another OPM's territory, but when a king is several counties away from the borders of the realm it's high time to appoint a regent. If male and capable, it would perhaps fall to the regent to lead armies back home against uprisings, revolts etc.
Actually having to make sure that you have enough commanders for every army you use would reinforce the character aspect of the game — you'd need to breed or invite commanders for your armies. Plus, you'd need to rely on the nobles actually present in the stack, which would add more realism and prevent too much power gaming with a collection of separate leaders for all terrain types and other situational contingencies. And there would be much more emphasis on making do with what you have and making the best of it.
The advantage, however:
If your physical location started to matter more (it already does matter e.g. for trying to arrest a noble who's away from his capital), it would be a good idea to enable you to interact with characters within some reasonable distance from your physical location, even if that's outside your diplomatic range. This means that your young unmarried male courtiers and the wards/squires growing up on campaigns would be able to get married e.g. to Byzantine or Jerusalemite ladies when you're on a crusade. And that would ehance realism and reduce inbreeding. And occasionally result in inheritances. You could also arrange for marriages for the ladies from your court or for males who are not present but are e.g. your sons or brothers.
