...and yet it was a massive success that probably saved Apple from oblivion.
Why would it have had a PS/2 port? Previous Macs used the strictly Mac-only ADB connectors for mice/keyboards; Localtalk or RS423 serial for printers (c.f. Centronics parallel for PC) and SCSI for discs & scanners (crossplatform but expensive & with bulky cabling & termination issues - PCs tended to use bi-directional Centronics for 'consumer' products like Zip drives). Releasing the iMac without legacy ports put the boot behind the peripheral manufacturers and within a year or so we had a good choice of USB printers, scanners, keyboards, mice that worked on both PC and Mac (PC keyboards & mice were often USB with a USB-to-PS/2 dongle thrown in).
Apple has actually shown really good judgement over when to kick out old ports, floppy drives, optical drives etc: there's usually a great wailing and gnashing of teeth when the announcement is made, followed by silence a few months later when people realise how little they need them. I'm even realising that I never use the Ethernet port on my MBP except at home where a TB dock would make sense. I agree that they got rid of floppies at the right time. A floppy drive is a large component. Anything complicated like SCSI also deserves to be removed at some point.
Meanwhile, even today, desktop PC motherboards, including little Mini-ITX ones with limited connector space, have PS/2 connectors, as part of a ridiculous "port cocktail" of USB-2, USB-3, USB-C, USB with always-on power, DVI, HDMI, DisplayPort, VGA and the occasional RS232... If you want to attach 3 displays you need 3 different cables...