Anyone who has used Wapping will know it is not step free. Lifts lead to a mezzanine but then there is a further steep stair to the platform. While I'm sure tfl have no money to add a fully accessible lift(s) at the moment, I'd have assumed that they have an ambition to do so at some stage.
In a left hand - right hand - don't talk to each other moment.... The buildings above the site are owned by the GLA, but are now being offered for sale, without any clause allowing tfl to subsequently gain access for lifts.
Given how narrow the platforms are I very much doubt that you could put together a safety case for allowing wheelchair access to the platforms at Wapping - which rather negates the value of installing lifts.