It's mostly about rigidity and roughing out large amounts of material (or using larger tools). It might be an option to entertain if he does more steel work by far, but it depends on the application since small tools and/or fine details wouldn't take advantage of the added rigidity.

About the pricing stuff, I'd say don't think of it as the sticker price but rather as the direct minimum price...except that you actually know what it is unlike when buying a car.
Part of the reason they don't haggle is because they're virtually the only industrial manufacturer that advertises their prices right out in the open. It's even worse though, certain other companies won't even give you a ballpark quote unless you agree to entertain an "engineering consultation" where they surreptitiously identify the size of your operation and how much cash you're willing to fork over. On the flip side, other manufacturers won't even give you tech support over the phone for a used machine unless you pay them thousands of dollars for a "license transfer." It can get pretty rough out there...lol