The reason for this is that it forces players to make intelligent choices about the CCs they take. Struggle with casters? A root won't do you any good. Know you're facing a lot of fear breaks? Don't take that, then. And it cuts down the overall number of CCs available to existing players. This, to me, is far better than the current trees for, say, warriors, where Storm Bolt and Shockwave are both on trees with two DPS abilities -- although Dragon Roar is a knockback. These two abilities would be far better off on the same tree, perhaps with Dragon Roar as the third. Bladestorm could then join another CC break + damage increase -- Avatar -- on another tier.
Lore also mentions, in the blue post after the break, that they will not just look at talent tree CC, but at baseline abilities as well. What's more, given the removal of CC abilities, CC breaks will need to be slimmed down, and that is on the devs' radar. In a subsequent tweet, he adds that DR categories are being looked at. With 14 at the moment, this is also a welcomed change.
Hit the break for Lore's full post.