Short and simple.
I liked the old functionality of the Media Mode buttons. When you chose a particular mode, all options for the other modes were hidden in the tree and the Action Window.
My image library really wasnt, and still isnt, big enough to worry with using anything more than Explorer to manage them on my external drive so I would just put MC into Audio mode and pretend that it only handled Audio. I could even have it start up in Audio mode and then I would never have to see any of the options for the other modes period. It was sealed after I made a blank PNG replacement for the buttons and the unused Media Modes all but disappeared from my life.
As it stands now, the Media Mode buttons are useless. Moreover, redundant. They do no more than the same thing a simple click on the corresponding branch in the tree would do. I still use the blank PNG for the buttons, so I rarely know they are there. However, given their uselessness, it seems to me that they are just added bloat. Unless (hint, hint, hint, hint) you guys should happen to bring back the old functionality of the Media Modes, then I would say leave them there.