The criticism I heard on DeutschlandFunk was that now they can't build chargers into thin lampposts or other places with space constraints.
It also makes chargers more expensive both in production cost and in maintenance, as you have to support a display and physical buttons and stuff, all that for a "legacy payment method".
Presumably the payment terminal doesn't need to be built into the individual charger itself. Just like paying for parking in a large car park, there aren't parking meters on every individual space, but rather you can walk to a central terminal to pay.
So on the one side we are pushing all kinds of contactless payment methods, incl. credit cards, only to call them "legacy" once those don't result in yet another walled garden but rather the opposite.
It also makes chargers more expensive both in production cost and in maintenance, as you have to support a display and physical buttons and stuff, all that for a "legacy payment method".