How many models does Apple produce? Now, how many combinations can,say, twelve different models of six limbs make up?
"Crafting a joint to only attach to your cybertorso" does not grant a 10% Essence cost reduction - why would it? The very reason Essence costs are reduced is eliminating redundancies, thus making implantation less invasive.
And how do you know what exactly was optimized in the example cybersuites, when we know nothing of the implants' inner workings?

i dont like full replacement cyberware suite. But i dont see any reason why there would not be suites for both legs, both legs and torso, both arms, both arms and torso etc..

In some SR3 book they mention that Doctors like install cyberware in pairs, its easier to tune and it keeps body balanced . So in my opinion whole body replacement suite isn't good idea, but there should be 2 or more suites when all installed are full replacement.

something like:

Head+ears+eyes suite for people who have had huge head trauma
Legs+torso suite for people who have fall from 3th floor and totally shattered they legs and pelvis
hands suite people who have lost arm/arms and need to have two cyberhands to keep body balanced

"Sir, we've just found the perfect test subject for our cyborg program."
"Very well, prepare the tank and get me his brain. You may feed the body to the ghouls, but keep some DNA samples in case we have to clone some spare parts."

I know you're kidding, but the cyborg rules say that adults work badly, right?

"Let's find out why. Perhaps this one works better than test subject B4."

There are issue with Adult Brains, but they are not completely horrible... at least you are not raising the ethical questions from using Children... of course, Whimp brains are the way to go in the end...

Following in this post is a list of megacorps caring about "ethical questions".

No Doubt... But it does have a certain Squick Factor that is just Oh So Wrong...

Lol