agree completely, but isn't that what hot wallets are for? to have wallet for your payments, that does not have all your funds in it
with fiat, you also do not hold all your funds, when you have to pay for bread and milk in the store
A different passphrase may be used to access long-term storage funds, or a different physical hardware wallet altogether. When making bigger payments away from home a hardware wallet will still be useful and more convenient.