The problem with BA doing that is that they will lose even more premium traffic. They currently have an extremely high number of frequent fliers compared to other carriers and if they were to reduce their level of service to lower than that of AF, KL and LH then they will simply lose custom.
It is all well and good saying BA should do this and do that but the matter is that BA are in a rut they cannot get out of. They are very limited to what they can do at LHR due to the slot constraints. They have no way of keeping business travellors. Taxes are rising to ridiculous levels in the UK now, with that stupid distance tax coming in whenever which will basically crush the 12hr+ services from LHR on price compared to a hop over the English channel and much cheaper taxes.
My personal opinion is that for BA, they should adopt a similar style to VS. High quality business, premium economy and a decent economy class. However, I do feel there are a number of routes that BA do benefit massively in the F cabins (LAX/DXB to name a couple) so I would guess that maybe they have a mix.
Something needs to be done but they have very little leway and the future doesn't look bright while taxes continue to rise.