Why should a phone sit flat on a table? What's the advantage of that?

I seriously don't understand this (common) complaint that I see. If anything a slight tilt makes the screen a bit more readable.

I don't want/need the whole thing to be flat but I do prefer it to be stable. For instance if the plateau were a bit thicker so that the camera lens was flush with the surface (even just an extra bar sort of inside the plateau) it would mean that when I put it down it would never rock back and forth when I'm tapping at it on a table.

The problem with the one-sided camera bump is that the phone is unstable. It wobbles when you touch it, making using it while lying “flat” on the table incredibly annoying.