Originally Posted by
voidspark
Not sure. Just keep in mind that for instance, on my main my tank spec is a 3rd spec (meaning that if I want to tank, I have to respec). Since Blizzard is stubborn and somehow thinks tri-spec is "bad" (don't even start me on this), the CTA bag hardly makes up for the respec cost alone, let alone the time I put in - both to run the instances, and to respec, and to maintain a 3rd spec.
Also, since I primarily play healers, I like to have a DPS spec as a 2nd spec (I feel heal/DPS is more useful both for quests and for random groups than heal/tank), so if I really wanted to chain CTA bags I would have to level and gear a primary tanking alt to realistically get any reward. Then we're looking at the cost of maintaining and gearing multiple alts, especially in MOP, it's still pretty bad. Basically the CTA reward bag is pitiful and hardly worth the effort, unless you have a main toon that is a tank/off-tank.
Off-Topic: Finally for queues, at least for healing, there might be some larger responsibility, but there's also the painfulness aspect. As a healer you really have few ways to make a shitty, slow run go faster. As a DPS you can actually affect the speed of a run quite significantly, especially in LFR.
Possible Solutions: Add tri-spec in game, and give CTA bags for LFR as well.