I think the frustration is that around a month ago Zuckaberg himself was hitting the media to drum up speculation, "Is it time to add a dislike button". I think it's more a matter of failure to deliver on said hype as expected.

Simply, for around a month we've been challenged to consider, is a dislike button something you might use? "Ok I suppose YES". Well then here's the new features. "Wait?! Where the dislike button you mentioned?". "Dislike! And crap that reminds me you didn't add the dislike button I want to use right now to dislike that you left the button out!!"