Gums, no first hand knowledge, but I believe the A320 (and subsequent brand 'A' FBW) were certified via an "Alternate Method of Compliance" - AMOC. AMOCs get used quite a bit when new technology allows the aircraft to meet the 'intent' of the rule without meeting the 'letter' of the rule. They are quite common when new technology basically makes the letter of the rule obsolete. A classic example on the Boeing side was the implementation of EICAS - the regulations say that you need full time indications for all sorts of things, with EICAS those full time indications were suppressed unless the were not doing what they were supposed to (e.g. fuel shutoff valve - on older aircraft there were indicator lights that indicated valve position - with EICAS those lights were replaced by an EICAS message if the valve wasn't in the commanded position).
So in the case of the side stick controller, I believe Airbus took the position that the FBW flight control algorithms eliminated the need for the physical feedback.