I'd like to discuss this shift, and then express my opinion on the said path blizzard is taking. 
Lets take the whole heirloom phenomenon for example. It started as a way of giving players an edge when leveling an Alt, in the form of pieces of armor and weapons that grow in power when the character goes up a level, as well as increase the amount of experience gained threw mob killing and finishing quests.
These armor pieces are bound to account, meaning you can send them via in game mail to other characters you play, and the heirloom system will soon also include shoulder enchants and other rep grinding rewards so you will only need to "grind your way" there with one of your characters.
We can also examine the next quote from Blizzard official post on their message boards:
"The reality that some players play many characters regularly is something we are trying to embrace more and more. We are putting more emphasis on your account and less on your actual character, so we hope to chip away at those moments where you feel punished for being on character A instead of character B"
The said quote was written in regards to the new Random LFG system, but in association with the heirloom system development suggests that Blizzard are shifting the focus from "time wasters", that took a heavy focus in the game development in early days of WOW, that were there mainly to make you play for as long as possible so you keep extending your game registration, into a more reactive development methods, where you watch what the players are doing inside the game, and respond to make that part of the game better.
One might argue that the heirloom system is just a "time waster" in disguise, as it's main result is encouraging you to create more Alts hence extending your play time. However, I claim that its effect is only reducing the time you spent on mindless grinding. I honestly don’t think there are that many more players that would play an alt with the heirloom system, that would'nt have had'nt it existed. However I'm confident that there certainly be a lot less grinding for those player then without the system.
As evidence to my view of things, I can point out a lot of more changes that blizzard implemented into the game recently that reduce "time wasters" potion of the game.
To name a few:
- Mounts summoning is much faster now.
- And so are various actions such as professions item creation, fishing and so on.
- Implementing the portals system between major cities
- The teleport system that is going to be implemented in and out of instances (like currently with BGs)
In my opinion, Blizzard as a game developer feels it can now afford to be less "paranoid" about the success of the game, and a lot less concerned with the "what can we to make sure players don't finish content to quickly" thought, since it is obvious that players are hooked up by/ addicted to the game.
The game development can be more confident in the product, and invest more time in improving the actual game experience and in increasing the actual /plated time of the player.