The Pixel C is the first tablet to be fully developed in-house by Google. Not unlike the Chromebook Pixel that runs Chrome OS, with the Pixel line Google means to show off what's possible to build using their software platforms even if it's inpractical for most to buy.
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips