Nanook of the North (can be found on YouTube if anyone is interested in watching it) depicts an eastern Canadian kayak (Baffin or Labrador, IIRC) not Greenland. The scene where Nanook pulls several people out from inside the kayak was staged; the entire film has been criticized for its inaccurate portrayal of Inuit life.

: If you don't think Greenland Inuits carried much in their kayaks check out,
: "Nanuk of the North". This video is still available from some
: places.

One can't paint a picture of Greenland with such a wide brush. Certain locations remained ice-free year round, which allowed hunting from kayaks in any season. Greenland kayaks as a whole vary more than any other regional kayak type because of the wide variety of conditions found in a relatively small geographic area.

: My understanding is that most of the time Greenland hunters paddled a few
: months of the year in ice fields with not much in the way of waves. I
: haven't heard much about rough water conditions around Greenland.

I think this applies to most all native arctic people except the Aleuts, since they didn't have to deal with ice.

: My understanding of Greenland Inuit hunters is that they stalked seals on ice
: flows. In an ice field you would want to avoid running into and up on ice.
: The pointed overhanging bow works to avoid this problem.

While we can't ask the original builders and designers, we can infer that certain features found in specific areas were meant to help one hunt in that particular area since different conditions elsewhere didn't warrant the same design features. Some historic examples were more than likely designed and built in ways that helped in rough water that was common to that particular area. See the photo below - i can't think of any reason why one would build a kayak with such a massive and upswept bow other than to help it perform in very rough seas.

: The Greenland designs I've seen and paddled are not designed for rough water.
: I received a visceral lesson in why a peaked deck is good in rough water
: while paddling my Disko Bay in Narragansett Bay. A large boat passed by
: and I thought, "Oh boy, play in the wake!" Normally I quarter
: waves but this time I paddled straight and fast into them. The first wave
: lifted my bow and as I road down the face of that wave, my bow dove deep
: into the next wave. When my bow finally came up, all the water plied on
: that flat fore deck came together in a big rooster tail and hit me right
: in the face!

Many Alaskan kayaks had high, peaked decks, and speculation is that shedding waves was one reason they were built in that manner.

: After that experience I realize why the Brits modified their Greenland based
: designs to have peaked fore decks.

: Fine stems give a smooth ride in waves because they dive into them.
: Whitewater boaters learned years ago that fine stems that dive into waves
: stop your forward momentum, so you loose power, speed and tire fast.

I'm not sure where that would have come from - forgot how to paddle? Rolling kayaks has a pretty long history and tradition in Greenland and elsewhere, not to mention that Greenland is the only location where there has been more or less uninterrupted kayak use even into modern times; other arctic locations have not fared so well since the introduction of firearms and motorized boats.

: The Greenland Inuit paddled only a very few months of the year because the
: sea froze. I think they learned to roll because they forgot how to paddle.

Bottom line is that we can't know for certain why kayaks were built the way they were, since the original builders have long since passed.