The other thing to remember is how society works. Society decides what is an isn't acceptable and has shifted in the last 50 years so that certain expressions are no longer tolerated. This is society getting better - making it unacceptable to attack people for what they are. While you may not value publications like this they do play an important role in making sure the boundaries of free expression are not moved backwards - especially important when it comes to politics and those with real power and influence.
Why do you think so many fascist dictatorships begin by burning books?
Being able to ridicule and satirize our politician, public figures and leaders is a safety valve that lets us know that society is working and free and fair and isn't being taken over by extremists. That is why they are of value even if you cannot see the value in the drawings - it's about more than the cartoons themselves.
If people see their prophet as a leader / political figure then why should he be excluded from criticism? Keep him locked away at home and he's not a target. Put the blame where it lies.