Why can't I make a playlist on my PC while connected as MTP?

[AC Question]

I like to hook up my phone and access the SD card data from my PC at work. But I don't seem to be able to drag songs from the 'device' into Winamp, or WMP or VLC etc. I have my music in folders but like to grab songs from different folders and prefer a mouse over the small touch screen.
I also have an otterbox case which makes it VERY hard to remove to just plug the sd card into a reader to do my music managing.