2 out of 5.. that high?
I'm surprised it's as many as 2 out of 5. At least most ISPs are now spoon feeding people by coming with all their security settings pre-installed and set up. All people need to do is enter a key in and away they go.
The problem in doing this is that the customer doesn't learn anything, they don't know why they have to connect with a secure key and they wouldn't know how to replace their own router should it fail.
I'd rather have ignorant customers with a secure wi-fi connection than someone who thinks they know what they are doing but have it set up incorrectly.