Meh, I think at this point blizzard is just lazy. A new trading system? Really? I don't think, especially with the supposed talented people they have over there, that it would take this much longer and this much more fog to the release just due to a trading system, which they already have in place for a game like World of Warcraft (understanding that it would not be the same, I'm just saying they've done it before).
"Crunching numbers" huh? Dont want to rush it out so as not to disappoint eager fans? Kind of too late, even without a set date, from when they announced it, it already has been a disappointment, and let's face facts, it's not like it's going to be working perfectly out of the gate anyway, there will be patches. I think all this extra time they are spending will not be paying off so much. Not saying they should release a non finished buggy game either, but I think sometimes they can go this slow just becasue they're blizzard, but also because they're blizzard, they probably could get things done a lot faster than they are with the talent they have (or should have) working on it.