Good luck on trying to get a firmware update from Nikon on an old camera!

Lots of theories on why they're so few and far between .. many seem to think it's because Nikon got it right in the first go.

I seriously doubt that, as many new features come to light that are easily added via a firmware tweak.

... as a couple of examples: better/more accurate focusing algorithms .. and more importantly AutoISO feature with new tweaks such as recognising lens focal lengths and adjusting accordingly to suit.