This was a move that will revive M+8 a bit, while I think we should go back to the reward thresholds from Dragonflight - especially with the existence of Delves which kinda destroys the point of M+ 2-6.
M+6 is a good level for slowly increasing one’s inventory - that of Heroic (as the last two upgrade levels recall already require Glited Crests, which may be beyond the reach of HC players) - because M+6 is the Heroic Raid level.
I encourage you to read my thread on the proposed more extensive changes around Mythic+