I am convinced they were ordered at some point to include cameras. They definitely drive up the cost of laptops, especially earlier on when webcams were more expensive. There were so few practical uses in the early days and so few people actually use them today that I am surprised few laptop manufacturers don't allow for security.
I do calls with client teams multiple times per week. Developers, ops, project managers, etc. I would peg the number at 5%. I say 5% because on one recent call with 20 people there was one person using a camera.
Additional of all the people I know - friends, family, parents, children, etc., only one of those people use the camera on their laptop. Some use facetime on their phone. But even for the mac users, it's a complete rarity.
Unfortunately, they're not even as good as phone front cameras because laptop screens are so thin. So people who do a lot of video chatting typically set up an external webcam or even a real camera in video mode.
The camera quality is pretty obvious just by making Webex calls on a laptop. I don’t actually know if getting extra equipment is popular, just seen howto articles recently on dpreview.
Fujifilm and Canon have added webcam support to their DSLRs though, which is interesting.
