DIN connectors are not expensive, nor fragile (too young to have used cassette players with them?). They are however big. Which is why the industry started using mini-jack connectors. They are now officially sanctioned:
...which means that almost everyone using midi 2.0 between multiple devices will be doing it over USB, which is a shame because very few hardware synthesizers or controllers can act as a USB host.
That's fine if you're connecting everything to a computer, but it's kind of a step backwards from what MIDI used to be, which was an easy way to connect almost any keyboard to almost any synthesizer made in the last three and a half decades or so.
I've wondered if CAN bus would be a good modern-ish alternative to DIN-5 and USB, but I don't know enough about it to say if it has some limitation that's not immediately apparent but which would become a problem. (On the plus side, it's much faster than plain DIN-5 midi, allows longer wires than USB, and it seems to be supported natively on a lot of cheap microcontrollers.)
I reckon CAN would be a great alternative. It has inbuilt support for message prioritization, so important stuff like timing sync messages could have higher priority. Also it's differential so long cable runs are not a problem and it has good noise immunity. Oh, and it's a bus so virtually unlimited devices on the same bus, in any topology.
Oh, and also I've always wanted to use my synths in the car!
It would be nice if the protocol of the future was wireless and could support the actual audio as well though, but all that adds extra complexity of course.
