It is physically plugged into the computer so you obviously don't need an icon cluttering your UI. This is the Apple design philosophy you paid extra for.
Or it's physically plugged in, but the driver stopped working with the last OS update and it never bothered to tell you, it's just been using wifi and you never noticed, because there wasn't any indicators.
The cable being plugged in tells you nothing about the state of the connection at the upper layers. Also, the icon doubles as a shortcut to connection status and settings panels.
Do you think it's clutter? Drag the icon to the overflow menu, you won't see it again unless looking for it. This is why I value customizability and use Windows.