Well yes... a PHEV by nature is a compromise in having to carry two power units, the internal combustion and the electric batteries. Either or will result in the carriage of dead weight
Given there is only a 40-60 mile electric only range for the 450h+ on a long journey you will never get the benefit of the electric, though it will slowly recharge over time (reports are the internal combustion engine can recharge the battery), but otherwise you are hauling around a large heavy battery pack which isn't being used.
If you're using the PHEV for trips to the shops, work etc which is generally or just over the electric range, then the benefit is more clear. The anecdotal reports from the US for the RAV4 PHEV were saying that for most of the above use cases, they were either on the original tank of petrol or the 2nd after six months/1 year.
The UXe suffers a little from being a conversion from an existing hybrid (non optimal main battery placement) but again if you're doing the shortish journeys within the designed range, would work fine.
I'd see the NX PHEV as optimal for my use case where it's mostly around town to the shops, school runs, short day trips etc, but still have a car that be taken long distance if needed. Yes, I'm hauling a large battery which doesn't do much in this case. Conversely I don't have to worry about having to make stops for charging, and I don't need to have/hire another car just for long trips,