I see someone here who has never worked with Blender, nor with GIMP, and does not comprehend the production difference.
Can you use Blender instead of Maya, of course. It is much slower progress, as you have to redo the same item multiple times to get it to export correctly such that Unreal can work with it.
Can you use GIMP? Not for every task needed, which means you have to turn to other applications to finish the jobs. Again, time consuming.
Can we use them, of course, and we have been. We also have a few members with higher end applications (primarily Maya, although a few folk with Lightwave 3D and 3DS Max, but still less than 1/4 of our art volunteers have access to a usable form), and we have seen the productivity difference. One guy with Maya is faster than 4 with Blender, even if he is one of the guys with Blender.
That is why the KS, not because we need the tools just to work, but if we want to get this done in a reasonable timeframe, we will need the tools. So we leave that in your hands. Are you all wanting this sooner with the tools, or later without?