I think this letter is silly, but it is a partly a problem that Apple helped create.

The closed nature of the App store leads people to think that apps purchased through it can never be malicious, they probably think Apple check every line of code (if they think about it at all).

I am not suggesting that it is Apples fault, but in a closed ecosystem higher security is expected.

Basically this is the same problem we have been dealing with since the rise of Windows, users have no clue about security.