Basic point:

Nokia is assuming that most people think the N900 is a computer first and phone last (as they intend I guess).

Based on many forums and even people I know who are wanting the device, they are assuming it is a phone first, and a computer last, with internet and media in the middle.

If my perspective is even a third of correct, this will mean a lot of unhappy N900 owners. Seems to make more sense to have the phone functions out of the box than "later" and avoid the unintended perceptions.