The other side being USB mini-B, though, has problems. The mini-B connectors are notoriously fragile. C is clearly a win here. Using the same connector for both ends is clearly a win here. And moreover: laptops can and do (and imo should) have both A and C ports. So USB-C isn't as disastrous as a piano, which can only have one key interface.

Mini-B seemed to have an exceedingly short lifespan, even by tech standards. I have some mini-B gear, but micro-B seemed to quickly supersede mini-B. (Micro also has some fragility issues of its own, of course.)

You could have said exactly the same thing with USB itself was first introduced, though. And lots of people did: there were endless, massive complaints about the first iMac.

Right—I totally see both sides here! Some transitions are absolutely necessary, and worth the trade-off.

Part of the problem in my view is that, if you're going to make these sorts of switches, you ought to be planning ahead 30+ years. If you told me USB-C was going to be the last iteration of the format (at least for several decades), I'd be okay with some weirdness in the interim. By contrast, if you told me the USB forum was going to introduce USB-D in 2030, I would absolutely not be willing to put up with this.

USB type A/B connectors lasted for >10 years, but were obviously inadequate for most recent devices (which is why there were mini and micro B types, a type A “superspeed” connector with an associated "extended" micro B type, alongside a large number of proprietary other connectors), without even mentioning the worst type A misfeature of appearing symmetrical at a glance but not being symmetrical. Keeping type A/B as the default for another 10+ years would be horrible.

There is no apparent reason why USB Type C connectors will not last significantly longer. They support a much wider range of use cases (collapsing what were previously at least 4 or 5 different connector types into 1, and using the same connector at both ends), and were explicitly designed to be future proof. The people involved in the design were thinking decades ahead.

It is unfortunate that many device makers (e.g. people making power strips) have taken a while to adopt Type C. But in another 5 or 10 years the transition will just be a memory. At most you’ll need an occasional dongle for your legacy hardware.

The biggest future competitor for USB type C plugs is various kinds of wireless transmission.

USB4 should help somewhat here by effectively being a streamlined subset of the initial USB-C + Thunderbolt 3 specs, as well as finally giving a clear definition for how hubs should work (in my eyes, the one fatal flaw of USB-C so far).