I know this has been asked before, but if there would be one thing I could put on the wishlist, than it would be a better handling of non-player/third party libraries.
Yes, there is that 'trick' how to add thumbnails, but it is super time consuming, and I a simple drag & drop solution would be amazing - as would be custom tagging (at least brand and general categories).
I can understand why NI might be hesitant, as the visual browsing and tagging makes their player libraries superior in functionality to non-player ones, but this would make Kontakt as a browser for all the libraries power users have collected over the yeas so much more useful. With the amazing firmware 2.0 update of the keyboard, one would get a one-stop solution for browsing and controlling all the sounds from the keyboard (that would be a dream come true!).
Come on NI, I know you can do it!