Most things are this way now. Customization is mind-blowingly costly. It is often far less costly to give five features for the price of three, rather than providing some random selection of three of the five features. And that's reflected in the prices we pay.
You see this in clothing: You could have a dress custom made, fitted to the millimeter perhaps, with just the specific adornments you like, patterned so as to appeal best to your own personal sensibilities. Or you could buy a dress that is fitted to one of a discrete number of sizes, representing a spectrum of sizes, but not necessarily any one of them being perfect for your body; styled based on some generalized understanding of what will appeal to a great extent to a wide variety of people. The latter will substantially less expensive than the former.
Another good example of this is subscription television. C-Band service actually allows you to select individual channels or big packages, as you wish. The math is jarring, for most people expecting this to be a nirvana for their wallet: Generally, you pay as much for six or seven individually-selected channels as you would pay if you just took a fifty channel package that included those selected channels.
As mentioned before, there are loads of after-market opportunities to add-on features individually, but that detachment from the package often either costs more, causes more work on the purchaser's part, and/or represents a warranty concern. However, it can be done, depending on the specific desire. For example, I wouldn't be surprised to learn that the price for installing just heated front seats is a large percentage of the price of the entire winter package, even though it is a small percentage of the material and labor costs associated with the full package.