'Only' 9-10 years ago the 1d had 4.2 mp and the 1dmkII 8mp.
For that time it was great, but now we have 5+megapixel screens, you are looking at almost 100% crops or 100%+ crops.
The reason i liked the 36mp of the d800, is that you got some future in your files, It's really hard to predict where the pixel race for screens will end, at the moment i can lean as close as my eye can focus to the screen and things still appear sharp, so i guess 8-10mp for a 15 inch laptop screen is about as far as is useful.
Is it useful to press your nose to the laptop monitor when the normal viewing distance is 50'ish cm?, I personally like it because I can see detail (hairs and such) which i cannot see from 50 cm, sure I can just zoom in on the image, But i don't know, I like it
It as about 220dpi now, if you translate that to a 42 inch tv screen , that would be 37'ish MP (estimate).
440 dpi would be 75+.
Is it necessary to be able to press your nose to the tv screen and still see a sharp picture when the normal viewing distance is 2-5 meters? ,probably not, but I would personally like it , seeing all that detail up close!
A bit of overkill of pixels on the camera (about 8-10 times screen resolution) never hurts imo, slightly out of focus images will still appear tack sharp!