Part of why Coils was so epic is because that single raid had an entire back story which was FFXIV 1.0.
There was the story progression from Dalamud, Nael Deus Darnus all from 1.0. Then there was a huge lul period while 2.0 was being built for the whole story of Bahamut to stew within players. Then 2.0 finally came and we got further development and actual Raid content about Bahamut etc. That content/story was locked behind the most challenging content.
I don't think anything else in this game has a chance to compete with something like that ever. I mean how could it? The players desire to do Coils was driven by the story from a whole other game's climactic ending, a 1 year wait, and then an epic story that could only be found by completing the most difficult content.