Prophet Muhammad also do married for political purposes and it shows his own desire is sacrificed for the greater cause
Many hardliner impose law beyond what Islam actually preach, just like the obligation to wear hijab for women in Muslim countries who adopt Shariah Islam, despite it is clear in Quran saying there should not be any compulsion in religion.
Why are you surprised at the people misinterpretation of Islam ? Anyone who has a clue about human nature should not be surprised