I think it's good to keep in mind that OSM already has moderation, though, just not in the shape of a formalized approval process. Instead, edits go live instantly – but are inspected, discussed and possibly undone afterwards. So while vandalism does get through at first, it will hopefully be short-lived enough that it does not pay off for the vandal.
Ultimately, I believe it comes down to weighing priorities based on the project's current needs. OSM's current approach lowers the bar for contributors and rewards them with instant gratification when the change is visible on the map right away. Because of that, I believe it makes sense when your focus is on growing the community. Stricter moderation makes sense once the primary focus switches from growth to preserving the valuable database you've already built.
Looking at Wikipedia, for example, they started out with a setup resembling OSM's current model, and switched to a more strict moderation process only once they had grown large enough to become the world's default encyclopedia.
Based on my personal experiences in OSM, vandalism is not yet a big enough problem to justify stricter moderation practices. But of course that is a matter of opinion to some degree.
Those edits are usually people adding useless businesses and phone-numbers. I've seen people advertising bitcoin-related business and general spam.
Map additions are probably generally safe, although there are some spammy ones for various reasons. Map edits are basically all suspect because you never know when someone is trying to sabotage something.