Wouldn't it be nice if we could select a Collection or Smart Collection to limit the scope when Importing From Another Catalog?
since a Collection is just a list of assets, and a Smart Collection just a search query on metadata, what would you like to import? just the (Smart) Collection definition or also the assets?
without the assets, a plain collection has no meaning. And in that case, where would you put them? in the same structure as the original Catalog or in a ad-hoc directory?
If you elaborate on this, and create a fairly detailed use case, you can submit an Idea to the Feedback Site and make other people to vote for it. If enough people will vote, the Idea could be considered by the Product Management.