I use the larger touchpad rather than a mouse when working at my desk, and I have to say that's been a non-issue—for me anyway. A slight touch/movement on the pad and I know exactly where I am (and the device really is just great...).
That said, the issues outlined in this article are glaring, and I do notice them when I switch to PC/Linux and a mouse and back. It's definitely something easy to forget, though.
The UX is designed to make most of the obviousness fade away and make the process an extension of your natural movements. Kind of like how a good band can take cues from each other without explicitly speaking or reading off of a sheet during a performance. But that doesn't help people who aren't adept professionals, or people operating under completely different circumstances.
I've hat as programmer many times this kind of discussion, about many features. And the lesson I learned goes like this: if somebody has an issue with something, it means they have an issue with something. Telling them "I don't have the issue" does not make their issue go away. In this particular case maybe they really want to see where they are just by looking - like the commenters above just said. That's pretty natural for them, we must agree.
