We can produce a TINY amount of work, based on amateur/charity/pro-bono work, using guerrilla film-making tactics.
But to actually produce a significant amount of free-culture media, the artists who make it have to have some way to support themselves on it.
Also, note how derivative "fan-funded" crowd-financed productions are. These are parasitic on commercial/proprietary marketing. People want more Trek, so Trek fan films are fundable.
But invent a NEW franchise? That's HARD.