It's easy, and it's lazy. Blizz want people to have to think about what they are doing and to have to prioritize. They want people to have to make decisions. Shield spam is just boring. There's no challenge to it.

No offense meant but that is a bit of a knee jerk reaction. To say discipline requires no thought or prioritization is way off. Frankly what requires less thought:

Scenario A: "Hey the tank just got hit really hard I better cast a heal to fix him.
Scenario B: "Hmm. The tank is going to get beat on a bit. I can protect him from some of that damage."

The whole penny saved is a penny earned (or mana) or a stitch in time saves nine (or a shield in times saves heals) mentality requires forethought. Add then whom do I shield, whom do I HoT, whom do I just heal and when.

Additionally heals for discipline take longer to cast, cost more manna to cast and generally heal for less than they do for holy. This combines to make the job for a disc priest tougher especially when leveling.

Lastly the response doesn't really answer my question especially why "For raiders, I think this is the real fix we were hoping for". Thanks for your input though.