Most people don't give a damn about becoming MSD or DM. As such, AOW is completely unnecessary to do the diving that most people want to do. As for rescue, I don't think it should be a requirement, and though it actually ISN'T a requirement for PADI or NAUI, every PADI shop will insist that it is. Quite annoying for those of us who want to take rescue but aren't interested in AOW.AOW provides a structured approach to improving your dive skills under the supervision of an instructor, and hopefully a good one. Having a lot of experience and a large number of dives where you have fine tuned your bad habits does not make someone a good diver. Conversely, getting an AOW certification doesn't necessarily mean that you are a greatly improved diver. The path to MSD or DM is not that long that one would need to skip AOW.
CAN it make you a better diver? Probably, with the right student and instructor. Is it more often just a money generating scheme for shops and agencies? Yes, I think so.