As a personal account on this situation --
Susano'o and Lakshmi Ex were two raids (well, maybe I should say Ex trials, but skill-wise they felt like raids I'd done in other games) I definitely wanted to do because they seemed fun. The struggle I encountered when trying to do Susano'o, back when it was still fresh, was finding groups on Party Finder. There were 3 different types of groups:
1) There would be plenty of groups taking people who had previously completed the raids and had gear levels higher than the actual minimum requirements of the fight.
2) There might be one or two groups doing runs to get a clear and expected people to have already made at least one attempt and know mechanics.
3) And every two or three days there might be a first-timer friendly group for learning mechanics.
So I spent several days trying to get into #3 and spent the wait time watching videos and reviewing fight mechanics. Never got one and just skipped to #2 because I'd watched the fight so many times on youtube 'learning mechanics' became a matter of just experiencing them first hand rather than not knowing what to do or how they worked.
Then I spent a few weeks getting into #2 maybe every other day and had no success at clearing with the groups despite working at it for hours simply because we couldn't make the dps check or we hit enrage. (I figure this is what I get for running Bard instead of any other dps except Machinist).
Never having a clear, I never joined #1 and eventually the number of PF's for these raids dwindled to nothing.
Now people will get it by doing it unsynced with whatever group we can manage to pull together while we're all well over-geared for the content. But hey, at least it'll be easier! And far more boring!
If that's the case for NA servers in general, I have to wonder if people would raid more if there were more groups willing to take 'beginners' and work with them rather than going the 'clear it quickly or not at all' route.