1. Digital audio means DRM audio
iTunes and later the Amazon MP3 store made DRM free audio a standard for audio you buy. This cat isn't going back in the bag. If you are whining that it's gettting harder to rip DRM from Spotify, etc. (music that you rent) then screw off, you're stealing and it's nobody's problem but your own.
2. Wireless headphones and speakers are fine, not great.
Wires are fine, not great. Shitty amps in phones are fine, not great. Bluetooth is great, your shitty $12 rig notwithstanding.
3. Dongles are stupid, especially when they require other dongles.
See 3, and use bluetooth.
4. Ditching a deeply established standard will disproportionately impact accessibility.
So will ditching DB-9 and floppy disks. Boo-hoo.
5. Making Android and iPhone headphones incompatible is incredibly arrogant and stupid.
You actually have a point here. MicroUSB and Lightning should be ditched in favor of USB-C. Yesterday.
6. No one is asking for this.
Remove a useless port for water and dust to get into? Sign me up!