That will be attractive to some passengers and I'd guess overall you'll burn less fuel than adding an extra landing & t/o so it's good for the airline
I'm not sure about that, ULH flights spend most of their flight burning extra fuel simply to carry the fuel they need to make the extra distance; the initial climbing rate and cruising altitude will be lower than the same airframe making a one-stop, which will punish fuel consumption. Hence the dearth of ULH flights during the high-oil-price years. Ideally they'd take-off with minimum fuel, reach cruising alt and then refuel from a tanker. But I can only imagine the hernia that'd cause in the FAA et al.