How small is too small for a bedroom for you?

Room for the bed (for two) and cloths...

Cloths take up too much room...

Honestly, I like the idea of having a tiny bedroom, that forces you to leave the room if you're doing anything but sleeping in there.

Of course, you'd need a whole other small room for your closet and stuff, and I certainly would not say that's ideal in terms of maximizing the value of your house should you ever try to sell the place.

That seems like a pretty good size to me.
Mine is a little smaller - about 12 X 11 feet, I think.

That should fit a queen bed, two night stands. It’s a bit tight, but I could manage that if that’s what I have.

can never have a master bedroom large enough

That's the minimum