The game is doing well, Raiding isn't. That's no surprise though. Savage is the only maker for clearing in this regard and honestly, hardcore raiding was never really the active thing players tried to push it to be, even in other games. Casual level raiding sees far more success buy in large and is a major justifies for the assets used.

That said, this census data comes from innate flaws.

First off, it requires minion data to mark it's metrics - this assumes that every player who obtains a minion item actually uses that item to fill it under their minion log. This is not 100% the case and some data is lost in that (though usually negligible.) Also, character metric data does not factor in Alts. Which, when you look at Balmung being the highest population server by a large margin, and the lowest clear rate - you can likely factor roleplaying alts to be a factor in that low percentage, as roleplayers are like to level their alts to have access to glamours, dyes, and equipment sets.

That said - this furthers the case of appealing too greatly to the hardcore crowd. Content completion dropoff is to be expected, but not this quickly. I would like to throw my opinion into the pile that some of these metrics was due to the rather obtuse gearing methods that were utilized this ilvl cycle. If you make it hard to get into and get prepared for something, the less likely players will do it. I still firmly believe that the 2.2 method was perhaps the best method. It is clear that incentivsing hardcore content by making it superior ilvl is not working as it's had no noticeable long term impact on raid completions.

Perhaps the inverse method deserves an attempt - making the gearing and preparation process for raiding to be quick and simple and focus on execution and teamwork, and have the reward focus for raiding not centered around a self-depreciating progression system. However the details of executing such a thing would be a murky discussion to have. There's no easy solution here but we do have to remember the goal would be attempting to widen a base that at this point is a narrow sliver of the active population. Broad sweeping strokes may be merited.