I agree with you that it is good to add passphrase for more security and the passphrase would not be kept with the seed phrase. Both of them should be kept swperatley so that if someone happens to see you seed phrase it is still useless to them because they do not have the passphrase. However, if you cannot acres your passphrase, you will not be able to access your wallet only with the seed phrase.
Yes, having safer data to access a wallet is quite significant. However, maintaining the confidentiality and security of this data is an obligation. Indeed, there is a risk of it being lost or deleted and something else and this happens very often. We have seen and read various articles about someone who lost data to access their wallets and in the end they were unable to get anything from their investments.
And this is enough of a lesson for us that data storage is very crucial. Of course, each person has their own way of securing this data. However, it is best to have a backup in some way. So even if we lose data on one device or item, we still have other storage for that data.