Personally I prefer this way to keep the different zones relevant and to be able to choose my levling path.
And I don't understand people who had issues while leveling. Neither on my priest or rogue I noticed any big bump in difficulty when I dinged. It felt quite smooth.
I can't imagine the zones without that scaling. My rogue already destroys enemy mobs in 2 seconds with 372 gear. If some enemies were still 110-115 level it would feel like you were doing WQs and farming in vanilla.
I don't see the fun in one shotting mobs just because you reached max level.