Dennis,
it's not a matter of biting, I'm putting forward a reasonable argument.
With Apple Care (which I think is a good idea on products of this type), I would say all parts will be covered for the reasonable part of the product's life.
Considering electronics, for sure any component can fail. Let's look at it: so can the CPU, GPU, jeez, even a single cap can fail on the board - and I'm not sure that RAM will be more susceptible to failure. Looking at electronics, you typically expect to see a bathtub failure curve, which means that you will be covered for the initial high "infant-mortality" phase and well into the "flat" part of the curve. On the contrary, with a factory-controlled specification, you have less chance of failure. I'm pretty sure Apple studies these statistics quite carefully.
We design and manufacture electronic systems (using ARM, Microchip) at our company and our most reliable systems by a long way are those designed to be purpose-specific, with no removable components.
I think that we're used to an old way of doing things and we need to adapt our view (I'm relatively new to Macs, but have been tinkering with PCs since the early '90s).