It's not that simple. You can't divide the numbers linearly by the same coefficient at the lower and higher levels (because a lvl 1 toon hitting for 4/1000 and mobs having 45/1000 HPs wouldn't make any sense). Your squish curve is bound to have angles or points of inflexion. And that can create problems.
Moreover, what Blizzard suggested just before MOP is essentially a gear squish, with ilvls getting reduced. And that means that a) if unattended, that will result in a reduction of character's power for lower level raids, and b) that Blizz will have to tune old raids accordingly if they want to preserve the same soloing power or face a QQ megatsunami. This will cost money and time that is better spent elsewhere.