My speculation is that there are increased rates of refund/chargeback calls from iTunes accounts with one-click purchase on, Apple is using this security measure as a preventive tool to prevent excessive chargebacks & refunds by making sure one-click users are absolutely rational about their purchases.
Do you have one click on in your case?
I do not experience this issue as my one-click is off, purchase of apps be it free or paid only only requires password verification in my case. All I have to is simply to re-type my CCV if I were to use my iTunes account on a new device.
My advice: Turn one-click off.