Kind of feel like you might be onto something there. I pretty much didn't play for Cata, MoP, or WoD other than a month or two here or there. I came back for Legion, ran Sunwell for fun and got the bow to drop. Ran it again the next week on the same character for transmog gear, got the bow again. Seemed a bit odd to me really.
That being said, there is only one person in my guild that has any of the Legion legendaries, and they have two of them thanks to that bug. No one else has even seen one drop in any of their groups. Seems dramatically low, considering there is supposed to be this hidden protection from never not getting one there. Not saying everyone needs one right this instant, but some kind of idea on changes of actually seeing one would be nice, especially considering some of them are garbage for certain specs / PvE or PvP focus.