At least 90% of my output (measured either from my digital introduction to date , or limited to the last year) is displayed on the computer only. I don't print much. I have only made two 20 x 30 prints and they were from my 3.3 MPx point & shoot camera. My shots go into websites, newsletters, and occasional publication. All limited size stuff.
Sure, I crop things and sometimes use all 16 MPx from my D4, but those shots fit comfortably into the remaining 10%.
My definition of 100% is only the keepers. I exclude the duds and OOF stuff and shots made by my finger brushing the release accidentally.
There are times when I'd like 36MPx or more, but those times are rare, significantly less than 1% of my shots. High MPx counts have their places but I rarely go there.