The biggest advantage for USB is for uncommon hardware configurations. For instance, I recently started using Yubikeys for authentication. Instead of getting a smartcard adapter for my desktop, laptop, and cell phone (god, just image carrying all that around!), I just have the one USB dongle that can plug into any computer or NFC to the cell phone.
I also do quite a bit of photography. Prior to USB, I honestly can't even remember a time when tethering a digital camera to a PC for remote shutter or instance image transfer upon capture even existed.
"Mass Storage" is one of those all encompassing things that USB does quite well these days. Need a boot device for a server? BAM, USB drive. Need to move just a couple GB of files from one building to the next where they don't have direct gigabit+ network links? BAM, another USB drive. Need to quickly access tools or drivers to fix a computer? Those are all on the micro SD card on my cell phone, which acts as a USB mass storage device when plugged into a computer.