Agreed this new refresh makes USB mp3 almost useless. Those saying put the mp3 files on a phone instead or comparing it to a cassette doesn't help the OP. that's kinds like saying buy a cassette player to play the cassette not use the built in cassette player... ( think replace cassette with MP3).
The option is there to use the device it should work like it did before the refresh, the option is there but it sucks.