I'm on record of being suspicious of 4e's monster design philosophy, but I don't mind this.
Monsters do need to be designed with how well they can survive against a party of PC's in mind. The 3e method didn't do it easily, without jumping through a lot of hoops and carrying a lot of extra baggage. It would be like trying to create a swashbuckler PC by multiclassing Fighter and Rogue. Yeah, it might look vaguely similar in the end, but you ended up with a lot of baggage that you just didn't need. While you could refine the 3e method to do that, it makes more sense to go for the jugular and design for the party.
Now, I still think that the monsters could be chock full of FAIL on the level of "Ally" and "Anybody," as in they could make very little sense in the world, and they won't be useful to the party at all except as XP speedbumps (and they won't be designed with their use as PC's in mind). I'm still concerned about this.
But giving me a kind of menu of options for the monsters is pretty okay. I would infinitely prefer it if such a system could be reverse-engineered for PC use, but I know they're not really concerned about that. I am concerned, too, with how well the monsters will work in the world. We don't need more Phantom Fungi and Ythraks. I worry, in short, that the design focus is too narrow. Which will probably make some really cool XP bumps, but it might not hold up the other levels that I need it to hold up on.