I was actually hoping for scaling technology because levels, to me, are bad and outdated for a multiplayer genre. It popped up on the radar a few times, with Blizzard commenting on it and saying it's being considered and worked on. In fact there was even a time where it looked like it got accidentally patched into the game and someone ran a dungeon with reduced stats. (They posted here with screenshots, but I don't feel like looking it up.) Then it all suddenly disappeared.
It was sort of a mystery, I thought it would be a great way for veteran players to scale down and play with low level buddies. Maybe it was going to be announced at Blizzcon? Nope.
Now it's pretty obvious to me they didn't want to introduce scaling level tech because it would devalue the worth of the leveling system. This is speculation, but I bet the conversation of the free 90/90 boost started about the time the scaling tech disappeared from the radar. I mean, why would you make the level system less important when you want to offer a paid boost? You would get less money.
I generally have no problem with a company doing stuff to make money, don't care about micro transactions, selling xp bonus potions, etc. I don't even necessarily care about selling a 90 boost, but I do think it's really shitty when something is done because it's more profitable and not in best interest of the game.