I agree and disagree
Agree: yes, that would help author to improve his item.
Disagree: I see the forums are full of “why my item was hard rejected, please help” messages and over 90% of authors of such messages submit really, really crappy stuff. Now imagine a reviewer who gets hundreds of such a messages. After reviewer explains it to author, I’m sure he will start receiving an endless number of messages like “but why??? my item is really good”, "why don’t you reply back to me? a friend of my friend’s friend confirmed he likes my item, so it must be good, approve it pleeeeeeeeeeeeeeease.
And that would mean a huge work overload for reviewers. Hence, high quality items will be in queue for much, much longer. I’m sure you don’t want it…