I get very well that you meant not all 16 but only the maximum achievable. :)
However, we want the AddOns to be "positive" awards, so they should only be displayed, when they are fulfilled. Otherwise, many people would see a lot of red dots (or any other color) on there badges indicating what they have not (and probably never will) achieve.
It's somehow similar with the badges. Not achieved ones are only visible in the details table, but not on the main page, where every badge shows an achievement of one sorts!