What's the use of the smartphone if you will adapt it in a smartwatch? That's useless, although smartwatches are more handy. But if you have a smartphone, you don't really need to buy a gadget that also have features in a smartphone, because that's a waste of money. But if you don't want to be hassle when you go out with your friends, it is preferable to use smartwatch. But being practical bitcoin holder, smartphones are more secured and safe when having transactions in bitcoin. Also the screen of smartwatch are most likely small and it is hard to read, in transactions, to ensure things before sending it into a wallet address is very necessary, so it is risky to use smartwatches.
Well, then.. why use a smartwatch for messages and calls when you have a smartphone that has the same features. Right?
Practicability is the answer to your question. But practical doesn't always mean secure. As I said, the smartwatch screen could act as a "Receive" QR code display for ease of use, as it would be easily accessible within the tap of a finger.
Another problem comes with usage though. You will only probably use the app on your smartwatch once every few months.. You don't use it everyday.