I have to admit that this is a brilliant move by Google. In one sweep, they have put the might of the formidable Android ecosystem behind ChromeOS. Well done. Chrome OS is instantly comparable to Linux and Windows if it can run native apps.
Windows and Linux have many, many more applications that are meant for trackpad-and-keyboard-with-'large'-screen interaction. Adding phone and tablet apps to ChromeOS doesn't make it instantly comparable to Linux and Windows.
It remains to be seen if more Chrome OS devices will come with touch screens or if app developers will modify their apps to work well without them.
Editing photos, video, text, is all less productive, slower, less capable, more superficial on mobile. Adding an instagram filter is kind of iconic for mobile's productivity factor in my opinion.
So is ChromeOS suddenly comparable to desktops if it can run mobile-productivity software? Of course not. Far from it.
This may change as we're seeing mobile/laptop blur a bit (iPad Pro with force touch, a stylus and USB ports for externals, 12" Macbook with Intel Core M processor, for example. Or any of the 2-in-1s, the MS Surface etc). Once we see Mobile software running on Laptops, and see Tablets equipped with a keyboard/stylus, converging around the 11" form factor, with ever improving mobile chips, then we'll probably see more 'real' productivity software.
But it's a bit too soon to call ChromeOS comparable all of a sudden. It's a great move, though. I remember you couldn't/can't even run Skype on ChromeOS. Soon, stuff like that will be of the past, without requiring massive Tizen-like investments to have developers completely rebuild a hundred thousand mid-high quality apps for your store.
Oh, because if you add an OS made for touch/small screens on a notebook equipped with a keyboard, that immediately makes it as good as regular desktop OS ?
http://lifehacker.com/how-to-run-android-apps-inside-chrome-...
But in future the simplest way for a developer to provide the same functionality on both desktop and Android smartphone will be to create a single Android app.