This is one change that i'm super excited about, and I hope it continues to grow as people get used to attunements again.
For me, and many people I know, they LOVE this change because it brings back a sense of accomplishment, and goals to achieve which rewards you with more content. More content is always welcomed. I loved every time I was able to get my rep with TBC factions up to revered because it meant more content was opened up to me!
The two new dungeons in in Legion are a great step in setting up more attunements in future patchs and expansions. I also love the fact that these two dungeons are mythic only, hence taking them out of the auto queue for LFD. Only those who really want to be there, will actually be there because:
a) they got themselves attuned, and
b) they joined or formed a group to venture into them.
Having rewards for those who want to put in a little more effort than press a UI button I think is LONG overdue, and it seems as though the community at large is in support of this decision, case in point:
http://us.battle.net/wow/en/forum/topic/20745115631
(community upvotes and support for the change)
http://us.battle.net/wow/en/forum/topic/20745136057
(downvotes, combating one of the few special little guys who cried over this)
Overall A+ on Blizzards part. Just another reason why Legion (and hopefully future expansions) will be awesome
Regarding the Attunement process for the 2 dungeons:
Originally Posted by Blizzard Entertainment
In the next beta build, both Arcway and Court of Stars will only be available as Mythic dungeons, unlocked at an appropriate point midway through the main Suramar questline. And in hopefully the build after that, you'll see a few extra items spicing up the loot tables of those dungeons as an extra attraction once they're unlocked. Their Normal and Heroic versions were already far less likely to be seen, due to queue mechanics, and this change is aimed at clarifying the role of these dungeons as endgame unlocked content.
It's crucial to remember that while the label "Mythic" may conjure up visions of hardcore raiding and may seem intimidating for those who haven't yet tried them, the main difference between Heroic and Mythic dungeons lies in the expected item level (810 vs. 830ish) and the fact that there is no random matchmaking available for the latter. An organized group of 5 players with experience and gear from Heroic dungeons should find success when venturing into Mythic. Higher levels of Mythic, accessed via Keystones, are where the major challenges lie.