If anything, pacifism is over-valued by absolutely everyone, anarchist or otherwise.
EDIT: A fair portion of anarchists I encounter (mostly in passing and on the internet, in places like Facebook or Tumblr) profess an attachment to the concept that the ideas can be spread solely via good argumentative skills and appeals to a person's morals or ethics or inner desires or sense of logical reasoning.
An equally significant portion espouse the idea that violence (a hazily-defined term that may or may not include anything from harsh words to property destruction to inflicting physical harm on a person) is inherently authoritarian and coercive and thus illegitimate for use by anarchists, even when used as a response to societal institutions that are coercive and use force as an inherent part of their daily activity.
I'm 100% tired of people making reference to Gandhi or King as an example of how "pacifism works" when it's a massive historical inaccuracy to claim that either of their movements weren't inherently reformist or that they could have achieved anything significant without the presence of militant radicals in or around their movements.
Equally tired of people believing that it's possible to simply "change people's minds" on a mass scale and achieve some kind of revolution without ever coming into forceful conflict.
The vast, vast majority of arguments for pacifism I've heard assert that it's either the only morally correct or the only strategically correct thing to do. I don't hold either of those statements to be true, and I think they either show a dangerous vulnerability to divide-and-conquer tactics (specifically the strategy of granting certain reforms to the non-violent/pacifist wing of a social movement and bestowing legitimacy upon them, while repressing the violent/militant wing and marking them as illegitimate), or a twisted understanding of how massive change comes to a society.