I just read an interesting interview by imaging-resource with Nikon’s General Manager of Design: Toshiaki Akagi, amongst others. After talking about several aspects of the D4 and other general topics, they got to the topic of why there is no built-in GPS in the D4:
Dave Etchells, Publisher, Imaging Resource: We had a number of readers, also, asking about GPS, and why you can attach a GPS receiver, but people are saying why wasn’t GPS built into the camera?
Toshiaki Akagi: We always have a GP-1 GPS accessory, then we want to use a GP-1, and if we include a GPS function in the camera, the camera would be bigger. And GPS still has a little problem, so for example indoors, we cannot get GPS data, then we are considering now to adapt the GPS to the next model, in the future. While you are indoors, the performance is not stable, so that’s why we gave up to install the function in the body as of now.
There is more, so read the rest at imaging-resource.com (found via nikonrumors.com).