Earlier quoted context omitted.
Why? I think 720p is the maximum need for a front facing camera on any device. What would you want a 4K front facing camera for? Most video-conferencing wont even allow more than 480p to preserve bandwidth.
Because the less pixelated it looks the more natural a conversation flows? Are you asking why is it important to have a good camera for online video conferencing? Look at all the guides that teach people how to use DSLRs as their webcams.
We are talking here about the average person's use-case