Why did Nikon choose 36 megapixels ? - why not larger ?

In theory, yes, my 36MP makes my image stitching easier in some respects when I want more gigapixels, but in practice - that is the practical working limit today.  Did you ever try loading 50-100 or more 36MP RAW images into CS6 even on the fastest, most powerful workstation that could be built?  I have for synchronous post editing. Let me tell you, its harder in many respects than you think as you want minutes to do even a single synchronous adjustment.  So until I can build a workstation that can handle synced images faster (and I have a monster one), 36MP is the practical working limit for a while.

I make tack sharp prints up to 300ppi at 10' x 30' for display and viewing from only feet away.  You can walk right up to the print (whole walls) and see the tiny detail in them. What specific subjects and benefits are you wanting from more MP sensors that you can't do easily right now?

Regards,
Mike