The deceased, unless they created the music, does not own the music. The purchased a license for them to listen to the music.
Bullshit. They most certainly do own that copy of the music, and none of your ridiculous FUD and RIAA shilling will change that.
It has nothing to do with the RIAA. An mp3 file is not considered tangible personal property, the media it is on is, however. It is also not considered real property (ie land and buildings). As such, there is nothing to transfer or inherit. Now, if the files are stored on a local computer, that is personal property and you can inherit that. However, your remote hosted drive is not owned by you and cannot be inherited.
I can buy a book and somebody can inherit it. I cannot buy a pattern of electrons called an ebook and somebody inherit it. You can only inherit tangible personal or real property. An ebook or other electronic media may have a license that allows it to be assigned to another person, in which case somebody else may have access to it after your death, but 1) most do not and 2) if they do, you still don't inherit it. Like the original purchaser, you don't own it, you just have a license to use it.