This is just a tad wrong, because they aren't abandoning it. They are simply relegating it to when it will be more appropriate to deal with it. Grapple, as presented in the PHB, will be the basic system anyone would need to know in order to grab another person. Since class powers are now where the coolness is usually found for a class, it makes sense to wait until a class that uses grapple as part of it's shtick to come up before putting in complex and cool maneuvers like Meat Shield.
It interferes with my enjoyment of the game to have abilities that anyone could do relegated to special pigeonholes that aren't available to everyone. If the stunt system fixes this by giving me a robust set of rules to accomplish coolness with, then anyone can use them, and my enjoyment remains intact.
If, however, the Bugbear Strangler is the only creature in the game at launch who can take someone and use them as a human shield without extensive houseruling, yeah, they are abandoning my needs, at least in this matter.
People argue that anyone should be able to do it... well, technically, anybody should be able to swing a weapon harder and with less accuracy, but we require you to pick up Power Attack (as a feat or power in 4e) to represent doing it, so why shouldn't we require you to pick up the class that focuses on grappling's Meat Shield power (when it finally gets published)? Why should it be included in the basic rules with classes that don't utilize grappling as a shtick (and not even require a power or feat to learn)?
It'd be great if we had rules that everyone could use that represents swinging harder and with less accuracy. I'd embrace putting something like a less-effective power attack in the core attacking rules. A stunts system might actually do that, allowing something like "raises" for more damage, giving less of a chance of success on the attack roll. I know it has been used to great effect in other games, why not D&D?
Why? If it's balanced and it works for an encounter, what's the point of rewriting it to fit with your new player ability, besides needless symmetry?
So that when one of my players says "Bugbear Stranglers are super fetch, KM, can I play one next week?" I can say "Hell yes, TV's Hannah Montana!" and we can all have milk and cookies.
Or, more practically, so that when the Bugbear Strangler uses his ability, it works kind of like what happens with the PC's do the same thing, just maybe better, making the ability more memorable, and ensuring that it adheres to the same rules, increasing consistency and my enjoyment of the game through that increase.