That's exactly why I got a tethered charger installed at home. Very quick to plug in.
PHEVs need to be charged to make sense environmentally. I think most people investing in PHEV are doing so for flexibility. Petrol range when needed (like Dergside's situation), battery for economy and lowered environmental impact. My X5 45e has a range of 80km real world on battery, which is a lot more usable than the 30km I was getting from the 530e. But a lot of people have low mileage and a 530e could easily be run on mostly battery.
Over their lifetime EVs have a lower environmental impact than any combustion engine car.