I'm a Muslim & I'm glad you asked this question - (sorry if my answer is too long)
Some people who call them selves Muslims have blown this out of proportion, letting their Anger overcome them.
As Muslims if we call for protests on the drawings of Prophet Mohamed we should have protested the same way when the movie passion of Christ was made as it is degradation of one of the Greatest prophets sent by God
Sadly similar to some Christians and Jews who do not know their religion properly there is a group of Muslims who do not know what they are doing or why they are doing so; in the process they have done more harm to Islam than the original drawing.
But here is the reason why you should not draw a picture of a Prophet (notice I said prophet and not just Mohamed)
A prophet is a Human sent by God to spread the word of God and if one does a painting of this man then with due time others would start idolizing this picture and praying to it instead of God, associating partners with God is an unforgivable sin
it is best to avoid drawing pictures of prophets as this would result in hanging such paintings/Drawings in important places and respecting it as if it were holy
Having said that, drawing inappropriate pictures of anyone for that matter is morally incorrect, imagine I draw a picture of someone’s mother or father in a degrading manner how offensive is that to the persons children, they may not react the same way but it is equally degrading
Why would a non Muslim want to draw a picture of Prophet Mohamed in a wrong manner (if not to anger Muslims) you can call it freedom but Freedom is a trial from God and to miss use it is to be answerable to God and we have no right to kill or hurt such a person
When Prophet Mohamed visited a town and the people of that town stoned him God sent the Angel Gabriel and asked the prophet if you wish god has sent me to punish them and our beloved prophet said No, Maybe some day they will realize their mistake and accept the right path therefore I forgive them
When the prophet was not angry of attacks against him why should we act in Anger
I conclude with a saying from the Quran
O you who believe seek help through perseverance and Prayer; surely, ALLAH is with those who patiently persevere.” [Quran 02:153]
Lets be patient and Allah is surely with those who are patient as mentioned in above verse of the Quran and we should not worry about their plans against Islam, we all should pray and Ask Allah to save us from their evil plans against Islam