This is a god awful idea and if all handsets doing this it is rubbish.
It is basically encouraging people to stay with the same handset manufacturer (assuming same spec for charger) unless a universal charger for all phones comes about.
It also renders the act of selling on your old handset to reclaim some money.
And finally it also encourages the use of 3rd party chargers which
iirc invalidate your warranty with the company/manufacturer.
So for us consumers it seems like a lose-lose situation, and just a blatant cash in on going "green" whereas it is basically lining their own pockets. How much of each handset actually goes to the WWF? 1.25% is utterly ridiculous. Actually try to do something useful rather than something like this, as making a box smaller just means another run of boxes to be made, more waste (dependant on the input size i guess) and I can only negates the overall eco/green theme!
I just hope that new handsets don't start being sold with the option to get a charger with it, where you have to pay a £10 premium...
Utter rubbish!