Mourn said:
You can do the same in 4e, unless you think the game police are going to prevent you from doing what you want in your own game. You'll just run into the same problem that happened in 1e/2e/3e when allowing a player to take a monster's ability: it might not be balanced for constant use by a player, as opposed to the one or two uses most monsters would get before getting defeated.
Exactly. By handling every special ability via the feat system, Third Edition gives the impression that you can restat any special ability as a feat and make it available to PCs.
And sure, you CAN do that. But whether doing that is a good idea is another matter entirely. In 3E, undead are invulnerable to critical hits, poison and a whole bunch of other things. Does that mean I can make a feat called "Poison Immunity," give it a couple of prerequisites, and call it "balanced?" I think we all know the answer.
Near as I can tell, Fourth Edition explicitly rejects the absurd symmetry that "an ability that's good (read: desirable) for a monster to have is equally good (still read: desirable) for a PC to have."
Character being used as human shield on occasion: Nifty! Nice change of pace.
Character being used as human shield every round, or every single encounter: A lot less Nifty. Rather boring, quite honestly.
However, by the time you've created 50 other
cool wicked unarmed combat maneuvers for your unarmed combat specialist to use, you aren't going to see "human shield" all the time. Because it's going to be vying for "screen time" with all the other nifty powers said character has.
As one ability, it makes for a boring one trick pony. As one of dozens of options, you'll see it just often enough for it to still be "neat" whenever it actually happens. That's the rationale for not releasing it as a PC option until you have a slew of unarmed combat abilities ready to go.
But the same rationale doesn't hold up as a power for one monster. Because it's not going to get boring if you see it whenever you fight "Bugbear Stranglers" because you probably don't fight those all the time. And given the rate at which villains die, this Bugbear unarmed combatant doesn't need 6 unarmed fighting tricks. Because he's only going to be able to manage about 2 or 3 moves before his guts are decorating the carpet.