I get that, I do.
I see this as a race or marathon. Those of us who played in Legion, finished the race and got our trophies. We got to show them off while the content was current.
(This applies to other titles, mogs, mounts, etc)
Just because people finish a race in 1st, 2nd and 3rd place doesn’t mean they call off the marathon and send all the runners home. People still get to finish.
The prize in wow, isn’t really the trophy. It’s having said trophy before everyone else.
That’s why Blizzard doesn’t remove the mythic appearances from raids after the raid becomes irrelevant. Having the mythic appearance from a raid while that tier is still relevent; that’s the true prize.
If players feel that their trophy (MT appearance, title, mount, etc) is diminished by others having the same trophy (at a way later date) after having overcome the same challenges to unlock that trophy (MT appearance, title, mount, etc) is something that requires reflection from the individual.
They’ll need to ask themselves, “Why does it bother me that others may get the same thing I did, albeit at a later date?”
Blizzard removed t3 for years before finally opening an avenue for players to get it. Later, they widened that avenue toward its acquisition. Arguably, it’s harder to acquire now than any other tier, but that’s a different matter. The point is that an avenue is there.
Should the acquisition for Mage Tower appearances be trivial content? Not a chance. But should it be barred to players who’s only offense was not being there at the time? Certainly not.