Is Scotrail a franchise or a some other entity? Have the DafT interfered in the running of Chiltern, beyond granting it a long franchise, which has allowed a more long-term outlook? On the third, are you saying that when the railways were nationalised, there was no innovation? Some of these questions I don't properly know the answers to, but would love to be educated on by those with some knowledge of events.
I would say, as Nearholmer has above, that as long as the DafT is kept at arms length from day to day operation, and that if structures are put in place to allow reasonable investment and renewals, then the review will have been worthwhile.