Yes PP can add meta data to clips and whatnot but doing it in FCP X is faster and more efficient. For example: When creating a marker in PP and then dragging it out to make a range, does the video scrub as you drag the range? Um no. I have to guess and then scrub the video itself to find where I want it, and then drag range to that point. Flimsy at best. It is the time it takes to do things in PP that turns me off. Yes there are inefficiencies in FCP X but they don’t seem to affect my workflows as much.
Don’t even get me started about managing tracks.