1
general::
Also, what's the use of. What purpose or advantage is there in, as in What's the good of crying when you can't do anything about it? or What's the use of getting a doctorate in philosophy when you won't be able to get a job afterward? This idiom was first recorded in 1701.
American Heritage Idioms
2
general::
Phrase(s): What’s the good of something?
What is the point of something?; Why bother with something? • What’s the good of my going at all if I’ll be late? • There is no need to get there early. What’s the good of that?
McGrawhill's American Idioms And Phrasal Verbs