I wouldn't appreciate the smells associated with the interior of used diapers in any cabin, to say nothing of potential sanitary issues. Out of courtesy of others' noses and a desire to maintain cleanliness, the fold-down changing table in the lav is the right place for changing diapers.
As for nakedness, I don't really care. I'd tend to agree that you don't have to look. But to me, nakedness is not really the issue when it comes to diaper changing in any cabin.