It just got too expensive. The Nikonos R was the end of the line, with autofocus. Discontinued around 2001. Selling for $2000 for the body, maybe more or less on the used market. You can house an F100 for a lot less and have a wider selection of lenses, if you must have film.
There was a product liability issue too. It seems that the strobes could explode if Nicad batteries in them got wet, a not uncommon event. The battery cap needed to be vented to prevent this. That is essentially the difference between the SB103 and SB105, cap vented for overpressure.
I don't know for sure, but I would bet the thinking went something like this: Hey, we're getting sued because these darn strobes explode and it's bad for the Nikon name. We're not selling many anyway. Let's get out of the business and concentrate on our traditional SLRs. Another possible example of runaway lawsuits, but it's not gonna change.