In theory this would be an excellent feature. In reality it's a simple fact that only every 200th to 500th downloader user uses the existing rating feature.
And his rating doesn't even say that much. In a perfect world a 5-star ratingĀ means the downloaded file exeeds the expectations of the leecher
(quality- and contentwise). In reality there are users out there who don't even download a file and rate it with one star (sucks!).
My indicator that I always look for are comments by other users. Not only are the usernames of the posters visible
(which fends of the grumpy/destrucive kind mentioned above), but the comments are far more detailed.