I suspect some people are actually prepared to pay a premium for the convenience of e-tickets, and for contactless when in London.
Especially for families with kids; the adults can have a copy of all the groups e-tickets, with each having a backup.
I suspect paper tickets are increasingly considered to be a faff, and if you lose it, you are stuffed.
Like most people these days, I'm not a fan of paper tickets , however I do make an exception for Travelcards, and I accept that making them e-ticketable would be problematic.