Its not about 'going back'. Its about being smart and doing what makes sense.
Yes, before privatisation there wasnt a totally uniform strategy but BritishRail certaintly had strategy, both for the network and in term of branding and marketing different setvices.
This would not just be a BritishRail thing. It would also involve the government, local governemnt and related transport services like TfL.
The smart way of doing it is basically what Switzerland did in Bahn2000. You first look at your current network and timetable and think about what you would optimally want, make a priority list. Then you study and figure out what you can get for how much price.
Then you make targeted infrastructure and service investments to achieve those goals, and of course you coordinate between all the different stack holders.
In Switzerland you also dont just have SBB, there are lots of other imporantant organisation. RBB, SOB, BLS are signifcant in passenger transport. And of course the local governments with their Transport organisations.
Is it in Britain somehow impossible for people to work thogether and come up with a plan?
This could even have been done during privatisation. Japan has many private railway and do a lot of integrated planning.
Its just a weakpoint of UK governemnt.