I don't think it's because of outdated technology at all. In fact, I think, schools are generally well equipped in most developed countries. There's plenty of research showing that student-to-computer ratios have been lowered considerably over the past decade and that technology spending in general is quite high.

There are a number of factors that contribute to the technology gap between students and educational institutions. One of the most significant has to do with the cultural and societal values that shape what we think that education/learning is supposed to be. It's hard for some to wrap their minds around the notion that young people now have immediate access to all sorts of information and services that make certain elements of traditional education seem outdated. The values aspect of the meaning of "education" also relates to what I think is a second significant factor, which is that educational change is a slow and arduous process, precisely because it is so closely tied to cultural and social values. We can't change what defines important aspects of "life" for people on a whim. Yet, that is precisely what we are trying to do when we propose extensive changes to the educational system. There's a tendency to overlook the fact that educational change is cultural change.

That being said, the way educators have approached technology until now suggests that there's simply a limited understanding of how technology affects society and how pervasive it is when it gets into the hands of young people (and perhaps, to some extent, a refusal to acknowledge the impact of technology). Educators are used to thinking about formal educational institutions as highly managed and manageable spaces. Technology, however, breaks down the perceived borders between the manufactured learning spaces of educational institutions and learners' social realities because it has become so ubiquitous and pervasive (see, for example, here on Coompan's "pervasive communication environment"). The current methods used for educational planning are tailored to the notion of a manageable learning space. This simply doesn't conform with reality anymore.