You should have your entire computer FileVaulted with a strong password. . . and that would keep them out completely and ALSO out of iTunes and your iPhone and iPad backups, regardless of how weak the iOS hash might be. FileVault makes it all a moot point.
There are pros and cons to FileVaulting your computer. If you forget your password, you can be completely locked out of getting to your data. Not even Apple can help you retrieve your data. Of course, that is the intent, to completely lock out others from getting your data. If you take this course, then be sure you back up your data and have access to the passwords! A brother-in-law of mine is always having me do his updates on his machine, and gripes when I ask him for his admin passwords. Because he forgets. Then I have to find my notes on what his passwords are!
As you say, if hackers have your computer, so be it, you have more to worry about than your phone backups.