It definitely is popular. I believe the reason they used to build them with small rooms, and doors to seal them was due to the difficulty in heating them before central air and heat. Our systems now work best if we don't shut off rooms, as you indicated.
I like open plan...just need to devise some sort of protective dome to cover the entire house during hurricanes...automated, so I press a button to activate, and clear so I can see out. (I was promised a Jetsons future...and I still want it! )