Where will you hide away your storage without sacrificing your gorgeous open view?
The house was designed explicitly as a weekend retreat, not a full time living space. Mies could get away without that as a concern because of that.
How many lots in a city are there where you can live in a house like this without losing basically all of your privacy
This isn’t in a city. It’s on a large wooded lot far from public view. That’s also an important part of the prompt. Farnsworth sued the local government later because they rerouted a road/bridge a bit further down the river to a spot where it could vaguely/kinda look over her property for that reason as well. She lost, but the bridge isn’t really that close.
how the hell are you going to keep the indoor temperature comfortable?
Mies’ grandson designed and installed an AC system later for the house. At the time it was built, AC existed but wasn’t as commonplace/assumed to be installed in every building.
When it comes to design, any decent building is going to start with the program and location, and respond accordingly. Mies took these specific conditions and used them as an excuse to do a radically open house that wouldn’t work in other conditions.