As you have said, tools in general are weak in importing and exporting, chances are you won't be able to import it into the other tool, anyway. As long as there's no standardized format for exhanging this info, it's hard to support these features. In circuits.io at least you benefit from other peoples work on component libraries.

True - but non-cloud-based software will keep working even if the developers go out of business or have to increase their prices (unless it has DRM or is leased by the month) - my 10-year-old copy of Altium Designer still works just fine.