Of course the reason for the cert is to give badge collectors something to shoot for and help sell specialties. It's just a way to hold a carrot in front of their nose.
Nothing wrong with that, especially if they are given some reality checks along the way as to where they sit in the ocean so to speak. The problem is the name Master itself and what it implies. The same of course could also be said for "Advanced" .
I always preffered to call advanced open water 2 as it is really just an extension of the basic class where they get a few more skills and hopefully correct any mistakes. Again these people need to also know "where they sit in the ocean" so they don't get in over their head.
The PADI individual specialties program is a good idea in some ways as it can be done in chunks, but perhaps they could look at tying it all together with a final course before they issue a Master scuba diver card.
I guess that tying together is their DM course? - I'm still learning the PADI model so excuse me if I get it wrong.