It could be all good when the user starts from a single (master) key/seed. But can the user import a normal BIP32 seed? What happens to the UI then? (I look at the slides). Also, I presume some of the functionality wouldn't be available to every kind of wallets. Will it be confusing
I prefer to think users should not normally have multiple BIP 32 seeds. There is no reason to use multiple BIP32 seeds except you are a wallet tester or you also manage the company's money on top of your personal money.
- If you have multiple accounts, you can dynamically switch between them or the "Merged View" (give me all my access without categorising them in accounts, like "flatten layers" in Photoshop, for example, by showing a drop-down list at the space where title ("Wallet") should be.
- But, if you have multiple wallets, you can't dynamically switch them. Instead, you go to "Settings" and do the change (which may result in the app restarted and unsaved form lost).
So in short, a switch of account is made easy; all accounts of the same seed are open so you receive a notification on assets on any of them. Switching seed is tucked away and there is no UI for it, with 90% of the people didn't know they could do that.
Treat it a bit like switching tasks on your PC (switch account) and dual-booting into another Operating System (switch seed).
The rationale for this treatment is if the users are accustomised of switching seeds, their assets are riskier since they would forget where are the backup of some of the seeds. But, this argument doesn't apply to Watch Wallet, since a Watch Wallet's seed isn't available at the outset.