Yes its a reason for that.
1- i want GG to work FASTER without a default texture, just a grey color is enough to test scenes, no need textures etc.
2- it looks more Professional like any 3d software/ game making / editing engine.
for prototyping i don't need to see th textures all time.
for example when you create something in a 3d sioftware like 3dsmax, yuu dont have any texture, everything is grey / menus and 3d objects.
showing 3d textures in realtime take a lot of ressources for nothing!!!!
In my experience this is something this engine need to have, an option who enable/disable every texture on the scene, just for testing, when you want to try your game (example: unreal engine)
Im sure this is something EASY to put in place!