One of the unintended consequences of franchising is the focus it gives route by route, at renewal every 7-15 years.
BR did a lot of good things, but it never had a systematic view of how to develop its services.
To be fair, the government didn't have a view either, other than cost reduction.
BR tended to jerk from one lot of hard-won investment to another on favoured main lines, and most of the rest was left to crumble away (which is why we got such poor services in the north and elsewhere).
These days, things are more open and focussed, with both NR and the franchise bids required to target investment for growth, in each area.
Abandoning franchises, whether public or private, would just bring back the amorphous unmanageable blob that the BR railway was.