In my opinion, the passive traffic you get for existing will be neglible in comparison to any traffic you would get from marketing.
Doubly so for assets. You would have to have someone looking for that exact asset at the time it has its 5 minute fame of being published.
If this is something people search for, you can also create devlogs or blog postings and link to those, if you do not have the project yet. Those are indexed by internet search engines.