Let me bring in another bit of food for thought.
Assets should be really cheap because they have nothing exclusive to them. I buy them, potentially 1000 more people buy them, the will show in 1000 more games and make my game look cheap because of this. Yet you still bring in industry prices for a single exlusive asset as a justification.
Imagine I bought some trees. No way to change their shape. The same tree shape will pop up in countless other games, making my game look cheap.
What you have to realize is that when you make the point ‘Anyone from a hobbyist to a full development studio can afford that and use it for the rest of their life in any project they want.’, then that really is not a pro, but a contra for the assets.
(Sorry for singing a bit out of tune)