The fact is, Foursquare has a truly excellent place database that's well-curated by users and is highly accurate due to the nature of their product.

Facebook does not. It has a mess of duplicate places and incorrect names due to the nature of their product. Hopefully this will be an impetus for improving their location database, but until then I don't see it being a better experience at all.

A contrarian "What if" question is fun and good to ask, but it's not automatically valid.