I researched the usability testing Gnome made, and I found only 1 related to Gnome3 but if you can point me to the study where they found that removing system tray is a good idea I really want to see how this study was made.

The truth is one more more Gnome3 designers that had the vision on how Gnome should look, that branding should be non optional, they did not know what XFCE is.