Earlier quoted context omitted.
It isn't just a gimmick, it is a legit feature when working from home and you don't want everyone to see your messy kitchen or bedroom. Sadly the chrome app version you have to use for ChromeOS doesn't support that feature anyway :(
I use Xsplit VCam in hangouts. There are a couple of other programs that do the same.
However, as we were using it for work conference, I felt like I was adding some goofiness to the call and didn't like that. I ended up moving the camera to show less mess, and then eventually actually cleaned up my mess.
Plus, VCam only works in Windows.