We have a problem of expectations. Mines of Moria™ has been a poor endgame. It is an excellent mid-/late-game area. The problem is just this year of waiting for Moria to no longer be the endgame.
Shadows of Angmar™ had a great endgame at level 50, with three small Annuminas instances, one small Angmar instance, two very large Angmar instances, one twelve-person raid (the most popular endgame target), and one full raid. There were large targets to fight in open areas, and the battlefield instances were strong late additions. It took some time to accumulate all that, but you had most of the options for most of the lifecycle.
Mines of Moria™ has had a weak endgame. Six instances with (often annoying) hard mode available, mostly with “unintended behavior” such that folks got their radiance gear far more easily than one can now. A raid that was just one big fight for twelve people. Then a second raid was added: a smaller fight for twelve people. Now there is more activity beyond that, although I cannot comment on it because (1) I have mostly been on break and (2) it is radiance-gated, so it is unavailable for much of the playerbase.
As an endgame, not stellar. As a mid-game? Wow, that is a lot of options as you pass through. In retrospect, all that level 50 stuff was just something for us to do while the next tier of mid-game came along, as is this extra set of MoM dungeons. In retrospect, kind of a waste to have spent so much time developing content that was covering gaps in the development timeline, but you must do something to keep the subscription dollars rolling in.