People have different obsessions and habits.
I'd always thought of USB ports as a "maintenance" peripheral. They're like having a floppy-drive; thumb drive is analog to a 3.5" floppy disc.
You only need the ubiquitous USB2/1 ports for your kybd, mouse, joystick, game controller or receiver.
I use SATA-connected hot-swap bays and caddies for backup, but I keep spare HDDs in USB2 boxes, and I'd modified some of the latter to make eSATA external drives.
But you can build a DAS with Addonics parts (5-drive enclosure + PSU, port-multiplier) and connect with either eSATA or USB3. You can BUY a DAS with USB3/eSATA option. I can see the USB3 ports as desirable for USB3 flash drive use, but -- like I said -- I'm searching for a "deal" on a 64 to 128GB unit that has stellar ratings and performance. Ultimately, it's a "want" item -- not a matter of need. For need, you have your USB2 flash drives of various capacity.
You can also charge your phone and (nicotine-"etc.") vaping device with them, though!