However, regarding going by bus, I very much do not see this as an option. Why not? Because [...] passengers with paper railway tickets will be denied boarding ('coz buses no longer accept cash fares). Remove that obstacle and then for the able bodied this becomes an option.
Rail tickets are accepted on any reasonable alternative bus route in West London when GWR/HC trains are not running, or are not calling at certain stations due to engineering work (usual casualties are Hanwell, West Ealing, Acton Main Line and the Greenford branch).
I agree that PAYG travellers may be financially worse off, although for many users daily capping would have come into play anyway.