What if someone wants to lock his bitcoin for his future generation and wants to set up a lock for 10 years so that his children will not be able to transfer these funds for the next 10 years, or a business owner wants to pay his workers monthly salary in bitcoin and he doesn't want to log in every time he needs to do that? He just simply set up a contract that will send monthly salary to some predefined address every month. Another possible use case is to prevent any unwanted transactions from coming through. Like only whitelisted addresses can send funds to a specific address, transactions from any unknown address will not be mined in this way, and the receiver address can pay for the transaction fees. There are countless more possibilities for the use of a smart wallet, and I think this will be a much-needed development in the future. Also, using and securing manmonic phrases or privet keys seems inconvenient for many of us, so using NFT's or some other possible ways to make your bitcoin wallets back up grandma-friendly will be a major development for wide adaptation of the bitcoin network.
The problem with making this work with crypto in general is that in fiat, the process is automated but there is a STOP button to halt the monthly payments in case something happens. For example: Employee quits, or salary has to be delayed or advanced by a week, or the invoicing software isn't working and is spitting wrong amounts, or the payment increases or decreases, or the schedule changes.
Smart contracts do not have a STOP button (well in Ethereum they do, it's called selfdestruct() and destroys the entire contract - but not in Bitcoin), so if you need to halt the schedule for any reason, you can't do that currently using any of the available Bitcoin infrastructure.