So...how is this a damage issue? Yes, the monk can't boost her damage via Superior Weapons -- but she can boost it via Superior Implements (by my reading, anyway) and similar, so hey.
Basically, the monk has two ways of making unarmed attacks:
1. Monk implement powers. These work equally well with unarmed attacks, the monk unarmed strike, and weapons, giving the monk a feel of "it doesn't matter what I'm armed with; I'll kick your ass into next week regardless. The monk's the guy who will hit your buddy with a spear, then plant it on the ground and pole vault feet-first into your face--then pull it out of the ground and spin it in a spiral, hitting everyone in the room. So having the monk use weapons (or her unarmed strike) but not necessarily bother to hit people with them is exactly right.
2. Multiclass weapon powers, OAs, and other basic attacks. Here is where the monk uses her unarmed strike (or, you know, actually hits someone with whatever weapon she's carying using a Weapon attack), and it's where the monks Unarmed Strike (which is, after all, a Superior-level "weapon") comes into its own, and it does a good job of emphasizing that even when a monk uses a basic attack or multiclass power, they can -still- prove an effective unarmed or improvised/spontaneous weapon combatant. Sure, it doesn't happen that often (though with Pointed Step Style, a monk can throw a Javelin at a medium-length foe and then Flurry to hit the foe two squares away), but it's an important aspect to helping the monk feel right and multiclass correctly.
Also, Danny, keep in mind that it's not just the Unarmed Strike's damage rating that's irrelevant for the monk's powers--it's everything about it. The monk gains no advantage for using Unarmed Strike as an implement over just using Ki Focus (except for monks who have a weapon focus(unarmed strike), anyway), and no part of the unarmed strike -- not the damage bonus, not the proficiency, nothing -- is relevant to an Implement power.