Don't bark at me, this is just an opinion..just listen for a sec and see if this makes sense.
First of all, don't think about the way WoW does it..imagine it never existed.
Secondly, and this is just my opinion. Maybe 16m is supposed to symbolize some kind of "Hard Core" aspect.
You can run 8mans and get loot quicker, have easier fights and progress faster or you can go the "Hard Core" route and do 16mans, get loot at a slower pace and work a lot harder to progress but have that "edge" that the 8mans will never have.
I dunno, I'm high right now but that makes sense to me.
8man = "casual"
16man = "hard core"
Or option B, Index 4, column D....It could be bugged..like everything else in the game