Going from 8 ft to 9 ft ceilings adds 12.5% more volume. For an 1,800 square foot house, in a 30x60 ft form factor, that increases the surface area exposed to outside air by 5.55%. This would create a small increase in the heating and cooling price per square foot, but a similar decrease in the cost per cubic foot.
You missed something important: many people are moving from a much older house with poor insulation. They can double their surface area and yet see their HVAC bills go down by a lot because modern houses are so much better.
construction cost maybe, heating/cool expenses difference won't be so tiny, quite the opposite and it's not only about expenses, lower ceiling is also faster to cool/heat, so you have to wait shorter time
I can really understand high ceiling (in new residential buildings) only for people who use fake built-in second floor (dunno the word in English, maybe mezzanine by my quick research) for like bed or something, but what's the point then and why not build proper separated 2nd floor if you are building new house
The larger use of energy in HVAC is recovery from losses from convection, conduction, radiation, and air leaks. The one time heating or cooling is small.