I want to make sure that no one, when I'm on a public protected network, is able to view that I'm even on. The reason is that I'm doing confidential work, and when I'm on my phone, on 3G its ok because AT&T encrypts it for me. But on wifi, the admin could see what websites I'm accessing (no porn, to clear that out) and potentially hijack the data. If my ip is masked or changing, they will have a much harder time doing that. It's only when I'm traveling and on a wifi net.