I agree that one-button interfaces can be frustrating for the reasons you mention. What makes this one work for me is its anticipation of what you'll want to do next. For example, the sequences are designed so the most likely action comes up first. And there are only a few possible actions, so if you want a less-used one, it's not hard to get to it.

For a more complex device like a pager where there are many options you might like to do at any given point in the menu structure, I see how just one button would make the user experience worse.