use cases are different: Mosaic is the new layout solution for Plone, the layout editor; collective.cover will use Mosaic at some point in the future to edit its own layout; collective.cover is optimized for front and landing pages that are frequently updated; it solves many specific use cases that have been extensively tested in demanding production environments (government and news sites) over the years.
but we are getting out of the scope of this post: focal points and basic image editing are things that must be implemented in the core (maybe as a behavior that allow you to rotate, mirror, etc.), or as part of plone.app.imagecropping (focal points, autocropping, etc.).
those are very nice ideas that can fit on GSoC projects, so go and fill the form!