Saw this today from blizz.
-Scaling down gear and character stats for old content is on the list of things that would be nice to do, it is just a matter of when there will be time to do it.
Why? I like soloing old content when I was playing. Do the developers think "well it worked for gw2, it'll work for WoW"? The reason it works in gw2 is you also still get gear/stuff equal to your level from whatever you kill regardless of level, and the player gets roughly equivalent experience. If the rewards for doing old content is the same, and you need to look for an entire group of 10, 25, or even 40 for old raids, no one's going to do it. It'll be "Oh, a BWL raid? ..meh, I have my mog already."