You can still set an arbitrary-length passcode. I think they phased out 4 as too weak, so now 6 is the default, but you can go longer and it'll just show you a

You can still set an arbitrary-length passcode. I think they phased out 4 as too weak, so now 6 is the default, but you can go longer and it'll just show you a text box instead of 6 placeholders.