Return to exclusive instances/zones.

So after playing through the main storyline of Stormblood and clearing the final instance I REALLY loved the zone that we were in prior to the fight. It's so rare to get to experience something in a game that I could genuinely contribute to an absolute work of art like this area, so after completing the battle and finishing the storyline I was hit with some curiosity as to whether or not I could return to the area and was devastated to find out that I could not. I was wondering if it would be possible to allow us free roam of normally inaccessible areas such as the zones between raids, the lotus stand, azys lla, the sanctum of the twelve and now the menagerie? It seems like such a waste someone took the time and effort to create an area for us that is no longer part of the player experience. Would something like this be able to be implemented? What sort of stipulations would it encounter? Do they even still exist?