Exactly. I doubt most of the ChromeApps that exist today were made for ChromeOS. They were made because it was an easy and straight forward way of making a webapp on the desktop. Now, as OP mentions, everyone is moving to Electron and NWJS, neither of which works directly on ChromeOS.
The only upside I can see is that CrOS is soon going to support running Android Apps which may save it, but even then... Maybe they'll figure out a way to run Electron/NWJS apps on ChromeOS?
OP isn't calling out how it hurts CrOS, they're describing how it's the place that Chrome Apps are still available, and thus could have that functionality copied out of CrOS and rejiggered to (continue to) work in Linux.