These pundits are victims to a basic error in technology: they assume they themselves are typical users, and that their experiences and preferences can be projected onto the rest of the market. They rightfully observe that for them as consumers (which is shorthand for their financial preferences, product profile, experience, and demanded intensity of experience) the Chromebook doesn't seem like a particularly viable option.

Once you take yourself out of your own head, and consider people for whom price is important, who don't demand products outside what the browser provides, who don't have a tremendous amount of experience, and who don't demand a particularly intense experience from their computer, the Chromebook looks a lot more attractive.

The tl;dr of it is: don't assume the entire market is like you.