There are pros and cons to this.

Pros:

-People would be less willing to mix and match sets for BiS and instead opt for full gear sets of the same kind of gear.
-It could feasibly balance the casual and hardcore.

Cons:

-To get the full benefit, you would need every piece of gear, and most people get gear one piece at a time.
-It could feasibly cause a disparity in stats between casual and hardcore players.

I would personally like to see it on lower-tier sets, but not hardcore endgame sets.