The same happens on W7 and I have to say I agree, it is unwanted.
I still want to know the file I have is a jpg, or mp3 or mkv, whether I am launching them with MC or not. In fact, since, when im using MC, I normally launch my files from within MC, not using Explorer, I have turned off MC file association for just this reason. It's a small irritation, so small I hadn't mentioned it. But I can't think why anyone thought renaming them all "media Center file" was a good idea!