What is 'conventional'? Otherwise, basically what I said...

By "conventional" I meant the kind of emotional pacing you see in most Western television, or in most anime aimed at adults: less abrupt changes in tone, more emotional consistency, and a slower pace overall. I don't buy "coping space" as a complete explanation because that's a basic element of competent emotional pacing no matter how it's executed; the slapstick interludes in FMA et al. are a distinct (and fairly unusual) mode and need additional explanation. The demographic considerations in the grandparent are my best guess as to what that is.