I agree, and, like others, I am shocked we don't have this already. And since it's a sound it would be skinnable and/or removable if desired.
On short spinners where a break does not immediately follow, I almost never look at the point judgment because I'm busy repositioning my cursor for the next circle (or busy continuing to spin for the next consecutive spinner), so I'm clueless until the song's conclusion as to whether I cleared the spinner or not (unless I bother to look and see if my combo broke). Also, I understand that some of us like to purposely spin only to completion without a bonus to allow ourselves even more extra time to concentrate on the next hit circle.
I can't think of a single reason we shouldn't have this.
Also, I agree that we should display "50" judgments on spinners when players get a 50 on one because if we can get one, we should be able to tell when we get one. If being without it was authentic, I must say it's the stupidest item of authenticity I've ever seen. :p