Why do they need to do this? They already track people with Oyster and contactless which gives them journey information. This is just a convenient data grab and profiteering. I'm going to sound old and curmudgeonly here, but I'm starting to miss the days when we bought paper tickets with cash.
I know people working on this project, and that is absolutely not their motivation. They want to better understand the movement of people within the system, so they can design better stations, trains, and services.
The traditional way of understanding such passenger movements is by parking students with clipboards and people-counters all around stations, doing passenger interviews and such. This traditional methodology is not only hugely expensive, but the data it generates is spectacularly bad, and has lead to some incredibly poor planning at times.