Well said , & Mr. Bad Lama!! 
Couldn’t agree more, being able to customize and learn from these assets, rapid prototype, and modify these assets IS the point of the marketplace. For me, it’s all about learning the best techniques, which is why 's Star FX, and King’s landscapes are so appealing to me, as it usually costs hundreds of dollars to learn from the best.
I wouldn’t use the assets aside from minor props in an actual game (rocks, random small objects), everything else I would either modify, or build myself. 