Outdoor ice conditions have been questionable at points in the past (see: LA, or Wrigley Field, heck, see Omaha but that wasn't pro). Stars can get hurt walking out from the tunnel, but why put them in conditions (poor ice) that increase the risk? As far as "buzz", look even at this site: the luster of "winter classic" isn't what it was.
I'll say it again: The minute this costs an owner a player you'll see teams staying away from the gimick.
PS - Playing outdoors, on an outdoor football or baseball field, differentiates ... how?