As far as i know it was a change in the OEM SOPs. The supposed reason was to only use normal landing flap settings from F15 onwards. We have it as SOP now, however there is nothing against using intermediate flap settings like 2, 10 and 25 in the SOPs so those are still good. After all F25 (F10 as well) is a normal take off flap setting too, why not use it on approach?