I tend to think stereo listening, for me anyway, favors a bit more of a live room. Something that creates some ambiance of its own. Something that doesn't sound sterile. I think this is also due to how stereo content is mixed. However, it is what it is!I'd love to hear what your ideas of the two types of "good" rooms are.
However, for MCH, the mix itself (hopefully) contains precision information routed to the appropriate speaker (or, object) to convey the intended soundscape. One wants every point-source to remain that way like tons of little headphones surrounding you. As if you could have 360 degrees of tiny full-range speakers and select any point in space to make it sound like something was coming from there. Of course, I'd need to make sure that sound didn't get all fubar'd by the room. So, I want it dead as possible -- I want to hear nothing but each speakers' direct sound and I want it coming only from the direction intended by the MCH mix! That said, I know the ears have limitations w.r.t. localization (e.g., I believe we are better horizontally than vertically).
Of course, a dead MCH room sounds closer to headphones to me. Some may like that -- I don't. So, enter upmixers and other technology to enliven the room.
Again, I'm willing to be wrong. However, personally, I like live rooms for music and deader rooms for movies. I've always found 2ch music sterile in dead rooms -- I may as well listen on cans. I'm all up for a debate about why I'm dumb and I shouldn't feel this way.
edit: to remove duplicate info