I agree it doesn't make sense. Unless Google announces something in the near future that would make it more than just a web-browsing device...
You buy a computer with faster processor so it can support applications in the future.
The Pixel will be the same a year or so from now. I don't think the hardware is upgradable. But it will be handle resources-intensive apps coming in the future.
Imagine a video-editing app or 3D games.