It's an old, old shotgun shack, single bedroom, indoor bathroom (sorta), parlor (with baby grand piano, my contribution), and kitchen that is large enough for 2 small people to ballroom dance in, and it came with a #2 tub and a rust stain on the kitchen floor to indicate where it went on Saturday nights.
I've actually used it that way, when times were harsher than they are now.
The thing you didn't mention about unmilled 2x4s is the gritching splinters. They are not happy-happy, joy-joy making kinds of things.
The floor was worse.
/johnny
Splinters! Oh, yes. The 2 X 8s I mentioned were ceiling beams for a very low sloping ceiling. I might have gotten a splinter from one of them when I was a boy. Whether or not I did, I was sure careful around them.
No wonder so few people complained about the 1/4" shave-offs of milled boards...