Who would it benefit though? From PR we can get to City/Canary Wharf/Victoria/E&C/Farringdon/KingsX/Clapham Junction pretty easily. All a Bakerloo extension would give us is slightly better journey times into bits of the west end (only slightly better because tube trains travel slowly). They also look at how much it would benefit the areas around proposed stations, and Peckham Rye/ED are pretty far along on that gentrification scale (on the proposed peckham route there is an intermediate station at burgess park which would help with the scally gentrification figures, but probably not enough). Considering it will cost 5bn that isn't much of a return, so that's why it will probably go along the old kent road to provide new escape routes from New Cross, Lewisham and other assorted dumps out that way. If you are in this for the long haul then sure sign a petition and see what happens, but major infrastructure projects move slowly compared to most peoples life events. Once they have finished with Crossrail, have found funding for CR2 and built it, then find funding for the Bakerloo extension and build it, that will probably be in 2030. I hope to be retired by then and living in a place with much worse public transport (a caribbean island perhaps).