From your comments below I think there are some points in my question that needs clarification:
- By downvote I mean the negative rep on the question starting from (-1) that conveys that the question is of low quality and not every downvote he gets; its sufficient to notify the OP once for the first negative rep.
- This question is not duplicate to the above two though they seem to convey the same meaning(I prefer similar than duplicate.) I am not saying :"it would be nice to notify us" I am saying :"it is crucial to notify us"; bringing each question alone may seem a suggestion for improvement while I'm talking about a solution for a problem..
- You really seem to contradict yourselves: You don't want to bother the downvoter to write a small sentence while you expect the OP to check the reputation changes every now and then to every question in every account he has on the site just to make sure he didn't ask a low quality question!
- You say the many notifcations will bother many users. They aren't that much; few low quality questions and you will be banned
- Note that I ask to be notified about the low quality questions and not answers fir there is a difference:
- a low quality question will never be asked again(other questions will be always marked as a duplicate) while it's possible to have many similar answers to the same question.
- Questions are usualy fewer than answers so it won't hurt the OP to get 5 extra notifications
- I see the same system applyed to the flags and I don't see anyone nagging about why he should write something to inform the moderator.
- watching for the decrease in rep points isn't always helping though. Take this question as an example :I get 11 downvotes but still my rep is 12 that's +9 to me. So if I didn't really see the question I would think I did a great job. What about those who answer too many question; A '-20' wouldn't even be noticed.