If Blizzard makes the rewards too weak, they won't incentivize tanks to run more instances. If they make the rewards strong enough to incentivize tanks, it will be decried as inequitable for the healers and dps. Plus, too strong will incentivize some really piss poor dps geared noobs to queue as tanks just for the leet gift bag.
Kathy, I said, "I'm lost" though I knew she was sleeping
I'm empty and aching and I don't know why
Counting the cars on the New Jersey Turnpike
They've all gone to look for America