Now that location services are being used for a lot of apps (especially Reminders) Apple ought to add the ability to have your lock only set when you leave a place (i.e. your house). Until then I won't use one.OT, but everyone needs to set a pass code. I know it takes a few extra seconds every time you want to look at your phone, but it is better than the damage that can be done by someone with malicious intent that has your phone.
IMO passcodes should be default on and prompt the user to create on during setup. Many people would simply live with it thinking that's just the way it is, and it would save them a lot at some point.