Perhaps you haven't explained clearly enough, because I'm none the wiser. I made the association, not leap, from the post you left and actually asked if I had understood you correctly.
Many people here are probably aware of my sometimes caustic reponses, but I genuinely cannot see the merit in having industry ratings imposed on a personal collection. I would hate it.
Along the lines that tt2 has mentioned, I have experience of marking a song with a rating, only to find the whole album marked with that same rating, when it's most definitely not what I wanted. It makes it impossible to mark songs on an album with different ratings, and I have had to battle with one or two albums to get them rated with my preferred rating, not someone else's.
Anyway, as tt2 has suggested, you can send your idea as feedback to Apple, which makes more sense than posting your questio here. Especially as, to answer your original question music ratings - why isn't it automated?, would call for speculation on our part about an Apple decision, which is forbidden by Apple in their forums.