eTickets have been added as a way of getting tickets and, at the same time, the traditional ways of buying tickets have pretty much all remained available - station ticket offices have remained open, ticket vending machines have renained (and, in fact, around 1,000 have been added nationally) and you are still entitled to buy on train if neither of these are available.
So I do not agree with arguments that eTickets have reduced accessibility; they have not affected accessibility at all, it seems, as no-one's ability to buy tickets in ways that they did before has been reduced.
I do recognise that there is a threat to ticket offices. But, by and large, that has not happened yet. And, to some degree, that will be mitigated by the extension of pay as you go schemes.