So either ticket offices would be allowed to fall into disrepair, or they would be repurposed - quite possibly for staff accommodation at smaller stations when taking breaks from their 8 hours assisting customers to use the ticket machines?
At some (many?) stations, is it really going to be safe to have a staff member just lingering around a gateline or station entrance instead of being in a single location, with a seat and heating/cooling, to assist - where people know to go?
Staff at gatelines in all weathers are entitled to more regular breaks, so what happens when the ex-ticket office staff are frozen and need to go. Does the wheelchair user just wait around or seek someone else for assistance?
I get that ticket office staff may sell less tickets and that could mean getting rid of some equipment or even giving less training, but surely having people at a fixed location is more sensible.
What will probably end up happening is that you'll just have an information point (pod/kiosk) outside instead, which can get vandalised and will need power/heating, making it more sensible to keep the ticket office.
And if tickets are sold on the platform, where does the money get banked if the ticket office has now become a Costa Coffee?