Have you used the Radio feature in Play Music much? When I first signed up with GPM I uploaded my collection, and when Radio (or it's early equivalent) first came out, it seemed to heavily favor tracks in my collection when auto-generating playlists. I use Radio for discovery or listening to stuff I don't hear frequently, so it was kind of the opposite of what I wanted.
On topic, I use my 3.5mm headphones everyday, typically to watch video. I also use a 3.5mm cord weekly to plug into an amp/speaker system. While I'm not surprised that Apple had the "courage" to remove the jack, I am really concerned that Android manufacturers are going to follow suit, and will start to drop the jack too. I've noticed when shopping for laptops a few times over the last year, that some models dropped (infrequent) or combined (becoming much more common) the analog jacks, so it's likely inevitable, but disappointing. When my bluetooth speaker dies, I can at least hook it up to power and use it. But when I'm going to do yard work or other work where I'm on the move, if my wireless headphones are dead, there's nothing I can do about it but go without.
I'll also agree with the sentiment that if Apple was going to drop the jack, there might have been at least slightly less gnashing of teeth if they'd gone with something that wasn't proprietary to replace it. The last thing anyone wants to do is buy several pairs of headphones with different connectors (Lightning, USB-C, etc.). Bluetooth should be the answer here, but as many have already mentioned, it has its own set of issues.