What is the point of stash, by the way?
I remember, in Warband I used it only when organizing feasts, so I could place of bunch of everything there.
What's the point of having a stash in BL?
I used it to stash literally hundreds of horses I'd looted and thousands of units of food, but only brought them into my inventory when I was forming an army. Other parties in your army make use of your horses for purposes of getting the Mounted footmen bonus, which keeps them relatively fast, and the food's use should be obvious. At one point, I had several sets of decent starter armor and weapons around as well but that tapered off because the education system provided really good gear.
edit:
As I see it, the game has 3 levels of play: Adventurer/Merc/Trader, Lord (owns fiefs) and finally Ruler (has recruited other clans). However, the gameplay is not significantly different. Practically, the difference between lord or even ruler from an Adventurer boils down to 2 things, access to a stash and access to the fief menu (which is about as exciting as a self serve menu at any decent fast food).
Why should we aspire to being a ruler? What new exciting gameplay does it open?
Speaking only for myself, I found a lot of difference between the early, mid and late game experience. For my late game, I mostly don't even faff around with battles unless it is deliver a particularly decisive siege or save one of my settlements. Instead I spend most of my time just running around recruiting clans, occasionally launching distraction raids/sieges to draw enemy armies to my party (and away from my faction's other armies), dealing with serious settlement issues and generally making sure my faction is "topped up" in terms of garrison strength. The clans I recruit can handle the actual grind of besieging every settlement on the map just fine without me.
The one exception, where I'm more inclined to get involved in direct battle as ruler is the start of a war against a faction that has been at peace for awhile. They'll generally have high-tier armies, with huge cavalry numbers (in 1.5.10, at least) and lots of depth to support them (oversized garrisons to draw from, full notable slots). So I'll have to do a bit of baiting, chasing, prodding, stalking, etc. until I can get a good fight in and whittle those numbers down.
Once their armies are showing up with 50% of their infantry being recruits, that's when I go back to being the ruler instead of the commander.
(Full disclosure: I think Warband's late/endgame is terrible, so being able to finish with hands-off isn't a bad thing in my eyes.)