Competitive pressures are driving the move to the Internet. Say you have a company that has traditional, non-Internet ways of doing things. They're comfortable in their ways, and they've got their rationale and traditions and all that. When they find themselves losing accounts, losing position or losing market share relative to some other company that is organized somewhat differently, it is a real call to action. The pioneers are first, and they get the arrows in their backs.
Some companies move early, and then the herd tends to move all at once.
Similarly, the ones that move late may find that they're not relevant anymore. One of the deep issues about edges is that they are not trouble-free. Corporate e-mail policy is one. Some companies save e-mail, and they claim the right to access all of it. They don't want to be embarrassed by it.