Maybe my needs are much more modest than that of the average user, but, as a matter of fact, I do get by without using extensions from the Google Chrome store which are not open source. I do install open source ones from there, but I'm ready to download from source and avoid the store, which I do indeed do in some cases.

Even if Chromium's source is developed by Google employees, it being open source at least allows it to undergo scrutiny with respect to end-user-unfriendly behaviour.