The reason for only the original AF set (level 45-50) as able to be stored in the Armorie and no others is because originally the first AF set was only available through doing the Job quests, whereas all other AF generally is gained through end game tokens (usually Allagan tomestones).

Therefore the way of SE's thinking, if you need to free up space in your inventory you were supposed to just throw away the later AF sets and then just buy another AF set again if you want it back - all except the original AF set are considered expendable and throw away items.

Obviously this precluded the introduction of the Glamor Dresser, but given SE did not change it when that was added, then it's clear this is still SE's attitude towards it.