It is a webwallet.
I don't think webwallets are so evil. They are useful for small amounts, and they are good for adoption.
You can send coins like sending an email. Older people might find it useful and interesting, could be a way to discover crypto for some people;
I personally stopped using web wallets a long time ago, because even for smaller amounts there are non-custodial desktop/mobile wallets that serve the purpose quite well. However, I agree that for some people a web wallet could be the best option in terms of simplicity, because all they need for access is a password+e-mail and possibly 2FA if they decide for greater security.
As for transactions with other users within the Proton system, it could also be interesting if it were to develop into something like
Proton Payments, where users could then save on fees, especially at times when they are too high.