Few reasons here. Anytime someone releases a "vintage" version of something, inevitably a few things happen:
A) "Well it's not EXACTLY like the 2011 version . . it's just not the same"
B) "Oh hey, they're releasing an 8 year old ball again . . just goes to show they can't make anything better.
C) "Oh wow it's back!!!" 2 months later, completely forgotten
That's why they redesigned the IQ Tour Pearl, if they'd have just done a straight re-release, it would have gotten attention for a couple months and then gotten ignored. This way it's "fresh."
This is a way to pay tribute to a classic, but update it with new tech. I know some people just want the original back, but that's just been proven to not really work.