The question is do you want to have something that is high performance or something that you 'can get away with'.
We get it, you don't like the features of modern cars. Well sure if they built the car you would like, then CAN bus is fine. But that's simply not where the future is going, if you like it doesn't matter. Its simply not relevant when car CEO discuss what is needed for modern cars.
You solution of 'just remove X,Y,Y features' is just a laughable suggestion here. Its like saying 'you don't need a new graphics card', I play 'Star Craft: Brood War' just fine. Ok I agree, I don't play AAA games either but to criticize a Nvidia CEO for saying the need higher performance would be totally absurd.
Cars will get more electronics parts, more cameras, more safety equipment, more communication and so on and so on. Moving to higher voltage and PoE is simply a logical thing to do given that reality.
If Musk is so utterly clueless, what of the things he said is actually wrong? Musk even literally said its not 'hot shit', its just bringing things up to date. But that's the simple facts of the automotive industry, lots of 'we did it because we have always done it' and despite it not being 'hot shit' its really hard to change.
So in the automotive industry, such changes are great because if you are building millions of something, it makes a very bit difference.
Seems to me you are reading into it what you want to read into it.