GIMP still opens many windows when it starts but it has single-window mode. The single-window mode is more modern/pleasing to today's average user and one of main goal for PureOS is to be mainstream default OS for future of computing so every part matters and visual appearance is one of the main (together with security, privacy and freedom orientation).
We want now to default to single-window mode.
+Once upstream moves to single window mode, remove the patch.