Hm, design... as I remember, the last "bug" I reported longer ago a few times was "by design" also. Bad luck for me...
What about the possibility to change design in this detail?
Think of this:
I want to mark 200 files. Lets say files 130-230, 850-900 and 1000-1050. Is there a way to mark them at once without klicking 100 times?
Or this:
Someone else is using my computer (and MC). (S)He an wants to do the first mentioned operation in a playlist, selecting the first 100 files (marking first file und last file with pressed SHIFT key) and then presses the Strg (Cntr) key to drag a box. (S)He will duplicate the 101 selected songs in the playlist.
And then (s)he starts to whistle and goes his/her way. And months later I wonder why my playlists are so big (yes, know the option "remove duplicates", and will use it ;))