This moves things along for eventual Apple Watch independence.
The App Store is the obvious one but the Voice Memo app helps with that goal as well. I already use my Watch quite a bit with my iPhone left at home but almost immediately miss one of the most basic features that having a smartphone with you at all times you take for granted: taking notes, saving thoughts for later use.
With a Watch, you could dictate something into a notes app but dictation is far from accurate and too much work. Having a Voice Memo is more natural: “hey Siri, record a note”. And now you have your voice notes neatly saved on your iPhone, iPad and Mac back at home.