You do have matchmaking in BG's, normal and heroic dungeons and lfr. That content is matched for the lowest common denominator.
If you want to do challenging content in WoW you have to form your own group. It has been this way since the dawn of WoW.
And with the inclusion of raider.io in to the game then it seems that Blizzard is keeping up its focus on Wow as social and competitive MMOi