Edit: Had to make a more tempting title. Now that I got your attention... to the point:
It's been quite a time since Rated Battlegrounds got changed to 10 man only, and I read the reason was that not enough people were active in the 15v15 weeks.
I've played 30 games in the 15v15 bracket while they were still available, and I had no longer queues than I had in 10v10 weeks, and even if they were a couple of minutes longer I wouldn't mind. Main thing is that people should be able to enjoy more than 3 Battlegrounds out of 8 in a Rated bracket...
I loved AB, and hell, I actually liked SOTA as a Rated BG. EOTS was awesome as well.
It's just becoming quite boring to be forced to play the same 3 battlegrounds over, and over, and over again.
I love the RBG concept. It's the best thing that has been implemented into WoW since Battlegrounds. Don't ruin your best concept so far in the game, and bring back the 15vs15 bracket.
Thanks for the read~