USB-C's been out for nearly half a decade. Why aren't you on a 100% USB-C ecosystem already? Come to think of it, the only USB legacy device I have is a USB-A & USB-C Combo drive.
I dunno - why are so many accessory makers still launching new hubs with legacy ports? Why are even Apple still including USB-A ports on the iMac, Mac Pro and even the brand new Mac Mini? Why can't I buy a hub with 12 USB-C ports?
ANS: Maybe because there is demand for it? Maybe because there are still a ton of USB-A/B devices on the market, not to mention all the perfectly good "legacy" devices around.
Maybe because the majority of devices that
do have USB-C don't actually gain anything from using it and (unless you bought them from Apple) come with a USB-A cable anyway.
Maybe because until USB-4 takes off (if it ever does), the only USB you get from a USB-C port is the same single USB 3.1 stream that you get from USB-A (...Apple doesn't implement 3.1 gen 2 10Gbps over USB-A, but others do) - which is fast enough for all but the highest-end devices.
Maybe because the higher power delivery modes offered by USB-C are optional, so few devices use more power than can be delivered by USB-A.
Maybe because - on a 13 or 16" laptop which has plenty of space for ports - combining disparate functions like power, USB/Thunderbolt I/O and video (which don't need to compete for the same CPU resources) into a limited number of "universal" ports is just a pointless recipe for endless compatibility problems and needing unnecessary docks & dongles.
I fail to understand what permutation of misconceptions leads people to think that it is better to
waste one of only 2-4 potential 40Gbps ports to connect a charger, DisplayPort display, or pointing device... Maybe if laptops were coming out with 6+ USB-C ports and USB-C had really delivered one
cable for everything... but it turns out that laptop CPUs rarely have enough spare PCIe or DisplayPort lanes to support that number of full-featured ports, and we have a confusing dumpster fire of visually identical but functionally different cables...
Oh yes, and let's replace a magnetic break-away power connector (the most likely thing to trail across the floor, and the one connection that a laptop can afford to have pulled out unexpectedly) with a plug... and meanwhile, replace the plug for your 20 Gbps drive array that desperately needed some sort of retaining clip (which you really shouldn't have trailing across the floor even if you could have a cable that long and
really don't want to pull out accidentally) with an even smaller and easier-to-pull out one. Magical.
Funnily, in the few areas where USB-C
is better - like, as a single multifunction connector on a phone that lacks space for multiple ports, or as a replacement for the fiddly and fugly USB B connectors on peripherals like mice and trackpads - Apple have mainly stuck with Lightning. Duh.
Oh well. Worse is the new better.