Also, the cheapest way to improve an visio setup is a correct audio installation, with a good enough mic and a soundcard. ~200€ gives you something correct, and is a huge step-up when doing visio (got a entry/mid level mic + id4 Audient soundcard, it does wonders).
For people starting from computer cam + headphones, I'd recommend upgrading audio first (cheapest, biggest felt quality improvements for others), then upgrading the video setup as explained here.
Having said that, there's no arguing that a better sensor and a wider aperture lens that gives a shallower depth of field yields more pleasing results.
The problem is, I hardly know anyone who's willing to pay almost $1000 to achieve such results.
If I'm recording a "proper" video, I need the higher quality that comes after pressing "record", and I jerry-rig a computer fan onto it. At webcam resolution I don't notice enough difference to worry about it, though.
That said, this could well depend on where one's heat source (e.g. windows and sunshine, radiators, ect.) are. Mine happens to be well away from anything else that generates much heat.
It has been excellent, and I at first used the kit lens which was honestly fine. But then I bought a cheap TTartisans manual focus 25mm f/2 lens for about $35 and this is even better. Manual focus is fine for me because I always sit in the same place in front of the camera, and this also prevents autofocus distractions if I move.
I use a very cheap $10 HDMI USB dongle, because you don't need 4k when you're doing nothing but Zoom calls. I also set the camera only to output 1080 resolution and 24fps which is good to know it cuts down on the camera heat.
Finally, for slightly more advanced operation, you can make sure to change the camera video settings to 24fps (or 30fps if not available) and a shutter speed of approximately 1/50. This produces the "180 degree shutter angle" that is most familiar to the eye from movies. (too fast and it looks stop motion, too slow and motion will be blurry).
Anyway, all this has made me appreciate video a little more, and also have a much more pleasing video presence (I think).