Remember it is the airport operators who approve what system of access control they have for their individual airports based on what works for them and more importantly, what the department will approve. Some airports already have very good systems of individual code issue or common code storage that can be accessed without any hassle at all.
Recently a few individuals thought it would be clever to post gate codes in the public notes section of the aerodrome listings within Oz Runway. No doubt done with the best intentions and could be argued, undoubtedly without success, that there was no lessening of the security outcome.
For the itinerant arrival, yes it can be a bit troublesome the first time until you know the procedure. The airports themselves usually have a system in place so they are not continually having to let people in and out of the gate.