I guess I too get annoyed about ratings. Granted if a game was titled "Mario's Wild Ride" and it was all about Mario "riding" Peach without falling off (You know, U,U,L,D,A,B,U..ooops Mario Fell off! Press B as fast as you can to get Mario hard again) Then one could argue about ratings systems.
As for ESRB ratings like the following:
MATURE
Titles rated
M (Mature) have content that may be suitable for persons ages 17 and older. Titles in this category may contain intense violence, blood and gore, sexual content and/or strong language.
ADULTS ONLY
Titles rated
AO (Adults Only) have content that should only be played by persons 18 years and older. Titles in this category may include prolonged scenes of intense violence and/or graphic sexual content and nudity.
There will be some who think certain software should be in the Mature category and some that think it should be in the Adults Only category.
As long as the app store allows comments about downloaded software, then this should keep problems from popping up.
I think personally a Dev should mention of any software has any content that is say, not safe for work, inappropriate for children, etc. But ratings "systems"<---(finger quotes) are just to generic and should be avoided. Simple, descriptive text, is all that is needed.
I'd hate to think that the community would have to worry about software being delayed for categorization under a ratings system. Or having software pulled for incorrect placement under the wrong rating etc. A good software description should make the end user aware enough of what they are downloading, and I trust no one is going to try to sneak in Porn images just to see if I get mad cause my 5 year old played the game and saw it.
Just my opinion on it...not that it is worth much.