[nicolaslem]

It's not like what you are describing is impossible today. With the switch to USB-C, iOS devices are compatible with a vast number of affordable adapters. Some of which add features and ports that realistically couldn't be physically on a phone like HDMI or RJ45.

[archerx]

So I would have to buy a usb hub + a dac. So much for it just works!

[nicolaslem]

What percentage of iOS users use a midi keyboard with their devices? 0.01%?

My desktop audio interface plugs right in an iPhone (USB-C to C), no hub or dongle needed, and provides audio in/out, 5-pins midi in/out, microphone preamp, etc.

If it comes to the flexibility of improvising a jam session with inexpensive gear, we are in a much better place today than 10 years ago when phones had headphone jacks. And I say that as someone who uses wired headphones extensively and carries a 3.5mm dongle everywhere.

[Melatonic]

The switch to USB-C was the whole reason I went to iOS personally. Lack of a proper headphone jack does suck (the Apple USB-C to 3.5mm is quite good however). Too bad we can't have both