Rated was taken away from lower level brackets because people were abusing it to wintrade in environments with way less active players.
As sad as it may sound, the thing that caused rating to get removed was probably all our attempts to report the wintraders. The increasing number in reports made blizzard realize there was a problem, and they decided to deal with it by simply removing rating from lower level brackets, which makes sense.
As much as we all want rating back you have to realize that it's not going to happen. It wouldn't make any sense. It didn't make any sense that we had rating in the first place, and it would make even less sense to re-implement it.
If you genuinely believe that rating is coming back to lower level brackets ever, then I don't think you realize just how low catering to twinks is on blizzards priority list.