It also doesn't have a Centronics parallel port either, but it's been ~15 years since I bought a printer with a parallel port. The Mini does come with an RJ-45 Ethernet port and that has been around almost as long as the SCSI ports. USB-A devices are still very common and still being sold.
Noting the limit on Thunderbolt ports, I would have liked a couple of USB-A ports with USB 2.0 performance levels for low speed peripherals so I wouldn't be wasting the high speed ports. In my case, I was pleasantly surprised that there wasn't a problem with using the USB-A ports on my Thunderbolt display for connecting the keyboard and trackpad. Unlike the experience others had with non-Apple monitors with USB ports, the my Mini does wake up when I press a key.