There is a certain movement of thought among Muslims, in which people believe that prophets (nabi) are not mere humans and the last prophet Muhammad (pbuh) is the greatest of all prophets.
According to these people, when you call the prophets name, he can hear you. For example, they believe that when you are in difficulty, if you call him "Help me, ya Rasulullah!", you will be saved. Or, if you call him "Shafaat ya Rasulullah!", you will be forgiven by nabi Muhammad in the Dooms Day. They also believe that he didn't die and his rooh (soul) is wandering among us.
This belief is shirk, and is completely incompatible with Islam. Christians started to believe that Isa (Christ) was an ilah (god) this way. For this people to make their own idol, totem, statue, sculpture Muhammad, there is only one step ahead, that is making an image or statue of Muhammad (pbuh).
Carrying good thoughts and good intentions does not prevent this terrible end. Christians worship Isa with good intentions. Christians too didn't have bad intentions when they started worshiping nabi Isa. Mushriks of Makka also had good intentions, they were only trying to reach Allah by worshiping their totems.
أَلَا لِلَّهِ الدِّينُ الْخَالِصُ وَالَّذِينَ اتَّخَذُوا مِن دُونِهِ أَوْلِيَاء مَا نَعْبُدُهُمْ إِلَّا لِيُقَرِّبُونَا إِلَى اللَّهِ زُلْفَى إِنَّ اللَّهَ يَحْكُمُ بَيْنَهُمْ فِي مَا هُمْ فِيهِ يَخْتَلِفُونَ إِنَّ اللَّهَ لَا يَهْدِي مَنْ هُوَ كَاذِبٌ كَفَّارٌ
Unquestionably, for Allah is the pure religion. And those who take protectors besides Him [say], "We only worship them that they may bring us nearer to Allah in position." Indeed, Allah will judge between them concerning that over which they differ. Indeed, Allah does not guide he who is a liar and [confirmed] disbeliever.
Zumar 3 (39/3)
In order to prevent this group from going further, in order to prevent uncontrollable love that would harm this religion, in order not to turn Islam into Sufism as it turned into "Christianity" in Isa's time, we don't print or paint image of Muhammad (pbuh), and we don't show his face in movies.