Inconsistent Mechanics: D&D Essentials Magic Missile

If 4th Edition D&D went to all of the trouble of replacing saving throws with defenses on a consistent basis, then why the hell did they undermine this good work by making the Essentials Magic Missile auto-hit?

Furthermore, this is a double-bad move, because it totally undermines the point of minions. Minions only have 1 HP because there's a chance that they'll be missed (about) half of the time. When you introduce a power that hits all the time, then you break the underlying assumptions on which minions are built, and you break your own rules.

If I ever break my own rules, please let me know.