787s have humidifiers for flight deck and crew rest air. Something like that is being done on the A350 and 777X as well, with humidification of first and business as on option. For the most part, the cabin experience is the same.
The colder the air, the less moisture it can hold, so if you cool air with nonzero relative humidity, the resulting air will have a higher relative humidity, which is why air conditioners have dehumidifiers. If you warm air, the result has a lower relative humidity. If the air outside is -40, heating it to room temperature is going to create a very dry environment that sucks the water out of you. This has nothing to do with bleed air or electrically heated.
There's also the claim when the 380 and 787 were entering service that they're pressurized to 6000 feet, while previous gen ac are pressurized to 8000. I'll leave it to someone else to say how often their Cabin Alt climbs to 8000.