One way to help limit the number of expansions indirectly would be to eliminate 3/4 of the staff the brothel has. You have beast carers and capturers, catacomb explorers, security, advertising, and whole separate staffs of bar and casino crews, strippers, masseuses, and then when you have them all, you have to...have a whole other staff of the same for the daytime shift. By the time you have enough girls to staff it all, so that you have reasonable customer satisfaction, you have the population of a small country. You either have to have almost NO actual whores, in which case your huge staff is very nearly losing money, or you have to expand like crazy and run through a LONG list of girls, which takes forever, before you can start all over with a second brothel, by which point, I'm always on random girls anyway.
The whole staff thing's a pain, when it comes out of the girls you have to buy, conquer or run into randomly on the street, and it takes forever. Myself, I kind of side with the original poster--I dread opening a new brothel in this game because it'll be a year before I have the staff for it and the list of girls takes a long time each turn to manage, when just one brothel is fully staffed.