Most parts stores don't have carburetor parts in stock, Most EFI systems use common factory style sensors, and I don't know about you but if I was to manufacture a car I would want my engines to last as long as possible to uphold a good reputation.
If I was gonna buy a new vehicle and had a choice between a manufacturer who's rep shows engines that last forever or a manufacturer who's engines only last 100k, I'm going with the one that lasts forever.