It reminds me of the issue of whether game cheats are legal or not. Activision is losing a lot of money because cheats are ruining the game for everyone. Here, the only "victim" is Facebook itself. And it's not cheating as much as automating a manual process. My opinion is that Facebook overstepped here. A net negative move with all the bad PR they got, of which they already have plenty. And the attentionthe plug-in got.