it was needed because all sport realises at some point that viewers are more important than money, because big viewing figures gets people talking, gets the media attention, which gets sponsors, which brings in money
Incidentally I haven't seen it mentioned here so just thought I'd put it down for the record - Formula E won't be racing in Battersea Park again next year due to a campaign by residents, so it's looking for a new London venue.
I don't think there's anything left of the old Crystal Palace track to run a race on.
Having just read a bit more about the circuit and consulted Google Earth. Part of the track survives and looking at it, it would require a bit of work but it would seem possible to restore most of the original layout. You could even have a section running through the Athletics stadium as they did in Mexico.
It will be around the Olympic Park, they have already had a design for a track there made up and I believe most of it is already in place. It will be much easier to get the ahead as the venue already has noise included in the planning and the locals can't say that the noise will be above the standard generated by anything else held at the stadium.