Retired for 17 years, I'll wade in late here. When I converted to the A-320 in the '80s I found the design of the rudder pedals rather odd, all previous types (see my profile) were configured to allow heels on the floor but one could easily press the upper portion to achieve braking without raising the heels. The A-320 forced you to place your feet at a shallower angle and to have them in position to apply brakes the heels had to be removed from the floor. To do this while still in the air seemed to be inviting a landing with brake(s) on, especially in a crosswind - it felt weird, I never adjusted to it and continued to keep heels on the floor until shifting position to apply brakes on the landing rollout. Auto brake use was SOP so this was never really an issue. I was aware that Airbus recommended otherwise but my employer did not require it.
What has not been mentioned above is that the A-340 and subsequently the A-330 had a much more conventional pedal design similar to that of Boeing, Douglas and others. A great improvement, one of several refinements to the Airbus product and I have always assumed it was in response to negative pilot input on the 320 design. I guess it was too late to retrofit the large A-320 fleet - or maybe intransigent pride played a part.