I agree with you about the convenience of using a multi-currency purse, because with a lot of wallets you can just get confused and it's very inconvenient.
In such cases, to quickly find the right coin, users usually use the search for a coin ticker.
For me, the inconvenience is passwords and key phrases. As you understand, for each purse they must be unique.
Yes, you are right, with a large number of assets is very difficult. The project can greatly simplify this.