You make it sound as though this intended to be a benefit to the consumer or the end product. Having worked on and around cars, and being friends with people who do for a living, I am really unconvinced that the manufacturers do a lot of this for any consumer-friendly reason, rather than simply trying to squeeze a buck out of you.
I can absolutely tell you that Volvo, for example, does what the GP is talking about, and then some. On an old school GM or Toyota, if you break a simple switch or knob, or things that really should just be simple devices, you can just pull it out, go to the junkyard or a parts retailer, and put the new one in and be on your way. Not so for Volvo (and I'm sure this has caught on in other manufacturers): if your switch or control or whatever fails, and its hooked up to the CAN-bus, whatever replacement you find simply won't work until you've gone to the dealership (if they even let you use a part that didn't come from there at all) and gotten them to flash the part and whatever other crap needs flashing like a BCM to get them to be compatible (I think just flashing the serial number of a BCM or whatever it needs to play nice with to the switch), at the tune of a couple hundred or more dollars each time.
So in essence, a stupid simple part, that should have been $5-10 that the manufacturer likely never would have seen a dollar from in the aftermarket, is now a $200+ dollar flash at the dealership, using the manufacturer scan tool, and also increasingly requires only parts the manufacturer can generate. So no, I really am extremely skeptical, given what occurs *today* that 95+% of the junk on CAN bus is there for any reason other than to boost dealership and manufacturer profits for no other reason than the fact they can.