They wanted diversity in the different specs. Like "hammerdin" type names for different specs. I feel they haven't actually made this goal just yet.
What they do need to do in order to make this happen however is to make even more diversity in each spec tree, and change drastically how different specs are played, make synergies with more of their skills for different specs. Which I'm all for.
Like make uniques feel even more uniques, like some uniques you get a summoned hero for a certain time. But why not take it one step further, and have the uniques also alter some of the powers the hero has in order for it to make synergies with an ability or such. Like glyph system used to do in WoW, or like the skill runes in Diablo 3. I mean the "hammerdin" and those type of names came from Blizzard(with Brevik in the lead) after all.
Now this will give the game even more depth, but also making the game more advanced and harder to "get" certain playstyles and such.