Well, to me it doesn't seem so odd, because ALL of their powers assume that you use an "unarmed strike" in some way, and the unarmed strike is just for those off times when you aren't using a power. How often those come up will depend on your DM (whether he provokes opportunity attacks or not) and on whether you have abilities or a warlord (or other character) giving out bonus basic attacks.
To me, its no wierder than my sorceress being able to bash people with her staff - generally she doesn't, but its nice to have the option. And indeed, if I cared enough to give her melee training (charisma), it might even be a good option. Its basically the same for monks, except they gave them an unarmed option as otherwise any monk that wanted to make basic attacks would be forced to carry around a weapon, which isn't what they wanted.
Mechanically, I really like the "monk as implement user" mechanic - it is a very nice ballance of letting monks use weapons if they want without making such a choice inherently better. Now, if you have a monk with a sword, you can describe a power as stabbing them, kicking them or whatever.