Earlier quoted context omitted.
One of the TakeItAparts here. We're certainly open to refining our Terms if others have been down a similar path before and have advice. My personal belief is to grant the user permissive rights, but we still need to worry about liability. We're certainly open to revisions.
Could you use a Creative Commons licensing scheme like Stack Exchange?
We have plans to add guide forking and merging in the future, so the licensing will need to allow derivative works. Our current license allows that while trying to still be reasonably fair to content creators (in particular due to the non-exclusivity). Since many car guides may begin by lifting the hood and removing the dust cover, they should be able to all fork from the same starting images, for example. There's also thumbnail generation, marketing screenshots of pages with guide images, etc.