I have absolutely no idea what Motorola was thinking when they got rid of USB Mass Storage, and I'm getting increasingly frustrated with the software development trainwreck that is Android File Transfer. Did they even test its compatibility with Mac OS X before forcing it down our throats? I haven't been able to copy a single file to my SD card since upgrading to Jellybean. Instead, I get a litany of error messages ranging from "Could not connect to Android File Transfer" to "Could not create a new folder on your SD card."
I never had these problems with USB Mass Storage.