I don't think there are that many "lighter-weight" Linux distros than Android. I mean Android flies on a Nexus 7, but even Lubuntu (with LXDE) struggles a bit on it. Sure there might be those "run it in RAM distros" or whatever, but I don't think those are too relevant for consumers. Keep in mind that mobile apps are on average about an order of magnitude "leaner" than the average Linux (or Windows/Mac OS) x86 program. So I don't think the "light-weight" argument is that good here.

Also, while ChromeOS may make sense for schools and businesses that have adopted the cloud fully, I'm not sure ChromeOS is that good of a option for regular consumers, other than having a more optimized interface for the desktop (a lot more than even Windows 8).

But for a consumer, does ChromeOS offer that much more than Chrome for Android?