Inno realized Milk rooms broke the games already broken economy and decided it needed to be flavor content instead of useful content. No modded fixes are expected anytime soon, that room likely isn't XML.
That or the fluid checks were not something she was interested in fixing so she... disincentivized that mechanic.
Not like you cant already mass kidnap Succubi and sell them for the same amount.
Inno found a solution without understanding what the problem is.
The problem is that outside of the very first steps of the game, money serves literally zero purpose and might as well not exist. And in the first few steps its just there to artificially delay you. But it's terrible at that, because you can still break the progression in like 15 minutes. It doesn't even serve the purpose of delaying you.
Edit: I'm high as fuck and going to keep expanding on the stupidity of this shit. The nerf is really fucking stupid from a design standpoint as well.
Like, the issue was that by capturing a specific type of slave, modifying them in a specific way, buying and upgrading a specific room, and then investing time into making money was too profitable.
So the solution was to cut the entire process off at the knees and break the chain at simply capturing and selling the specific slave is the most profitable solution. Which requires way less money to set up. Which requires way less management. Which requires in-game and real world time.
Like, you essentially made an entire progression path into a dead end. All without actually addressing the issue of the player making too much money too quickly.
Not that it matters, because my original point still stands. Lets say Inno nerfs selling demons into the ground. Okay, now we'll just abuse the enchant system which is also horribly imbalanced. So she nerfs that, so now we'll go with one of the other passive methods of making money until she nerfs that. And then people realize you can spam the fuck out of the prostitution system to get all the money you need.
And this is all without any real thought towards how much time you actually want the player to waste.
Even worse, if she actually does start trying to "balance" this problem, all she's going to do is highlight the other issues the game has. If you get to the point where you're selling items for money, the shitty inventory system is going to be super highlighted. If you start nerfing all the household passive income, you'll quickly highlight the fact that the slave system is incredibly shallow and has never been expanded past the really basic shit added years ago...
Okay, I'm gonna take another edible and keep working on the really overly complicated overlay injector I'm building for sugarcube.