To each his own. Not having to carry a phone when running is the best thing digital watches did to me.
Is it possible to store music for offline playback on the Watch and pair it with your Airpods for listening on the go? I'm not a fan of running/cycling with my phone so a Watch/Airpod combo sounds super useful to ditch the phone. I understand I'd need an iPhone for the Watch but I'm just curious if this use case would be possible.
Yes, and not only that but you can also stream Apple Music over LTE as well.
LTE with apple music works as well. Other streaming services such as spotify aren't yet supported without a phone.