Well, personally I find "KFC" to be catchier than "Kentucky Fried Chicken" and people were probably calling it KFC before when it was Kentucky Fried Chicken.
As for mutant chickens with no beaks and extra legs, to my knowledge we can't even do that. We can change the kinds of protein produced in goat milk, change the by-product of bacterial replication, but the removal of limbs is something completely different. It's possible to do, but you'd have to understand the genetic code so well and be able to manipulate it so well that you pretty much understand what everything does. This is *way* ahead of our time. While we might have an inkling as to what kind of protein a part of the genetic code might make, how does it function with the other proteins produced to make the cell function? And how does the functioning of the cell work to replicate in a precise manner to form a complete entity? You'd pretty much have to re-write most of the genetic code in order to get rid of their feet and beaks, not to mention to add extra legs.
Of course, you could selectively breed, but even then I'm not sure if it would be possible to get rid of the beaks and feet, and very impossible to grow extra legs, plus I'd imagine that it'd take a significantly long time if it *were* possible. There would be problems of keeping the chickens nutritious enough to be "harvestable", and they wouldn't be able to do the breeding themselves if they can't move.
Bleh. When I hear that FDA officials and Scientific American journalists raid the place to A) crack down on such an operation and B) Report this complex work of modern humans, or maybe even just a C) Reliable news source talking about it, then maybe I'll be willing to consider the feet-less, beak-less, extra-leg chicken theory.