I don't see this as anything new. People have always formed tribes around events whether its at work, at the coffee shop, the bar, or meetings.
People are firstly lazy, want to fit in and rarely will stand up for what the believe in, if they actually believe in anything at all.
The Internet and social media just allows for larger and more anonymous tribes to join.
I agree forming an opinion takes time and expressing it demands backing it up with facts, not just parroting some loudmouth.
As for the photograph in question, the impact is from the fact that a monster can look so nice. Any anybody can be a monster.
In the US we want our monsters to look menacing, otherwise going to the mall can be too scary. Nuance and critical thinking are too much work.
People forget the monsters that walked amongst us don't all look like Theodore Kaczynski (sp?) the Unabomber or Charles Manson. Eric and Lyle Menendez, Ted Bundy, Richard Ramirez, and even Jeffrey Dahmer were all good-looking if not at least average joes.