It is indeed easier with USB sticks but not without some big trade offs.
Flat usb mp3s is really from dinosaur time
On the other hand Spotify has very dynamic content discovery capability, limitless number of stations and shared playlist, default album art (metadata) and most importantly: NO NEED TO UPDATE SONGS, millions of songs available at fingertips, thousands added daily.
Car companies are usually not software company, they should do one thing really good that is building cars and also work on very good integration with other services. For example, whatever stock GPS in your car will look hopeless compare with google map.
BMW probably has one of the better infotainment system but this is by no means a match of apple IOS/android. Car companies are adopting them though.
So at the mean time, while we are buying "in the middle" generation of cars, we also asking questions on forums like this to learn tricks and hacks to make fully use of what we currently have.