On the other hand, you need to consider that for you to have grown up "in a pacifist background" its quite an unusual event in the History of Humanity. In particular, it means that there's someone somewhere doing all the dirty deeds that keep the pacifists safe and unaware for long enough to raise any offspring. In the primal environment, uncompromising pacifists would probably end up darwinized!
I am by no means arguing that others should follow this philosophy. Merely explaining that, having grown up in a culture where we gave this idea serious thought, I found Ender's Game to be shallow and naive.
[0] http://en.wikipedia.org/wiki/Mennonites [1] http://en.wikipedia.org/wiki/Martyr%27s_Mirror
To clarify a little bit, it's not so much as of pacifism not being a viable strategy, but that it is a viable strategy for individuals or small communities, but not implementable on a national scale.
Eventually, the martyrdom of a pacifist, while a tragedy on its own, is not detrimental to the meme of pacifism. I'd say it's the opposite. However, if a group of people that follows the meme of pacifism is systematically harassed, I'd think it would eventually be assimilated by the other group doing the harassing. Even if most of the individuals are not physically harmed, the idea of pacifism is the one that suffers.
But of course... geographic isolation may take you a long way, I guess.
History shows that "running away" and other isolation strategies have allowed at least some groups of pacifists to persist through several centuries. Harassment seems to actually strengthen the idea of pacifism within many of these groups.
It may not be viable on a large scale. But that ties in to my earlier point: a viable strategy for survival is not the ultimate goal. Or, at least, it's not a universally agreed upon primary goal. We're not so special that our survival must necessarily trump everything else. Neither Ender nor anyone else in the book series seems to give serious consideration to the idea that maybe it's better to die than to kill. Again, I'm not arguing that everyone should agree to this philosophy, I'm just saying the failure to give it even token consideration comes off as a bit shallow.
Since I can't very well read it again for the first time, I was happy to find a couple of years ago that a narrative-astute friend of mine had happened to never read it. So I encouraged him to give it a try and was extremely careful to say nothing of the ambivalence I've had for it. He summed it up as pulp designed as a preteen want-to-be-a-superhero hook with an twist about on a level with a middling Twilight Zone episode. Thus ends my anecdote.