It's weird but when I was a kid I thought GEOS was a toy - I inherently rejected the graphical presentation of "doing things" over the "command line" (which was just BASIC for the most part).
Of course, this could be due to not caring for most of the applications launchable from GEOS.
The lack of launcher support (like legacy DOS support in Windows) probably killed it. If you were using it, you were also often loading native programs instead of it.
Something as simple as a double-click instead of having to reset and "LOAD * ,8,1" would have encouraged the practice of launching into a GUI first.
Of course, this could be due to not caring for most of the applications launchable from GEOS.