It sounds like yet another idea which favours passengers who are already predisposed to rail travel to spend less on their travel rather than one which widens the customer base. The latter is what the railway and economy needs, not the former.
There are existing loyalty schemes run by the operating companies with various objectives. Some sort of continuation of those will make sense, but the return is likely to be greatest for those making full fare travel.
These things always come down to a marketing decision about who needs to be kept happy and incentivised, what additional business is going to emerge, and how can cannibalisation of existing revenue be avoided.
