Are they?
I run as much M+ as I ever did (granted, with static groups), have gotten my all-portals season goals every time so far (on track for this one), and I run 3-4 rank 11 delves weekly for the H vault slots + crests (although arguably I might not even need to, since I cap Guilded anyway and usually pick a Mythic vault item from the dungeon track).
The truth it, running keys past +10 is kind of an unnecessary effort for a majority of players. The same way running Mythic raids is. Nothing special here.
Time to add more tiers on delves and reward the player base with higher item levels.
And now we see the real agenda come out. 