I don't have to worry about my music being removed because the licensing changed at the streaming provider. I tried various streaming services and all of them removed music from me at some point. This isn't something that's particularly negotiable for me.
I can trivially add songs that aren't on a streaming service using youtube-dl or similar.
I can change songs by pressing a physical button on the side of the player, meaning it doesn't have to leave my pocket and I don't have to look at it. This is particularly useful while exercising.
You can do all of this with a smartphone, though. There are plenty of offline music apps for smartphones. There are plenty of phones (and headphones) with physical buttons to control music.
My main criticism is that this is all redundant hardware with basically no unique capabilities.
Even if the DAC is extra special, that’s something you can get on a phone via USB.
In my opinion, the iOS experience for playing offline music is going downhill, and has been since the iPhone 3GS era.
It gets more and more difficult to have a UI dedicated to offline music - you can disable streaming, but you can't disable the 'Radio' section of the Music app for example.
Similarly, the user experience has got quite a bit worse for navigating your catalogue: 10 years or so ago, you used to be able to click the Name of the Artist or Album that was playing, and it would jump to either the artist or the album respectively: these days, on iOS 15, doing that does nothing other than jump back to the currently playing song list (so current album normally), neither does hold-and-press. I have to navigate with the back button, or go back through library, and find the artist each time, or use search.
There are third part dedicated apps and I've tried some of them (and bought Ecoute and VOX), but they're not perfect either.
Smartphones are also generally a lot larger, so they don't fit in my pocket very well while cycling or running.
I need my smartphone to do a whole bunch of things outside playing music, and restricting myself to specific models with physical audio control buttons and small screens makes the market a lot smaller and would probably leave me with a poorer phone than picking one without needing to think about its ability to play music while exercising. I did this for my previous phone and the result wasn't very pleasant, so went with the separate players this time around.
Different headphones might be an option, but again a lot of the better phones are ditching headphone jacks, so it would be restricting my phone options.
you can still load songs directly. I use the controls on my earbuds to switch songs. Not as fine a degree of control but most of the time I just need to skip anyway.
I don't have to worry about my music being removed because the licensing changed at the streaming provider. I tried various streaming services and all of them removed music from me at some point. This isn't something that's particularly negotiable for me.
I can trivially add songs that aren't on a streaming service using youtube-dl or similar.
I can change songs by pressing a physical button on the side of the player, meaning it doesn't have to leave my pocket and I don't have to look at it. This is particularly useful while exercising.