Alt + Left Click to move windows has a tendency to conflict with creative workflow apps. While Alt can be changed to Meta in KWin's settings, Alt + Left Click shortcuts often cannot be customized in apps. Rather than making every user who runs into this problem change their settings, we should change our default settings to improve KWin's default usability. The fact that Alt + Left Click to move windows is older does not matter. We are trying to use Meta for global/shell shortcuts anyway.