There may not be businesses but there certainly are things worth taking out a loan on, workshops, granaries, fortifications, recruitment centers, region investments, new religions. They all cost money and sometimes you need to pay for them ASAP.
You're correct that right now its easy to get someone to just cough up some dough for you but part of my motivation to make this bank is I want to change the way people in BM treat money. We need more greedy people BM we need more frugal people in BM. I want dukes to stop handing out 100 gold to whomever asks because they need that money to pay off that loan they took out in order to upgrade their fortifications during the last war.
I believe there's a lengthy entry about this time of behavior in the background section. Handing out gifts to people is a display of prestige that fully fits the era. It's also politically rewarding.
It's hard to incite people to be greedy when the players (and even the characters) enjoy the same quality of life regardless of how much gold the characters have. Nobody ever has to chose between the comforts of a luxurious life and charity, because in BM, the comforts of a luxurious life are only charged to adventurers.
