Earlier quoted context omitted.
Not being Thai, I won't comment on his effectiveness and I mourn anyone's passing. But it would seem like it's a lot easier to be 'widely loved' when you make it illegal to feel or communicate anything negative.
Laws preventing criticism don't generally motivate people to hang pictures of the king in their homes. A more plausible cynical position would argue that the widespread development projects funded by revenue from the king's vast royal fortune bought the affection. But the Thai people seem to generally respect, even revere King Bhumibol, feeling that he sincerely cared for the well-being of his people.
obviously you never been/read about central Europe during Soviet occupation (1949-1991), Stalin pictures/busts everywhere, people cried on the streets when he died. In Poland we had _mandatory_ 'work holiday' celebrations on 1 of may. People would march on the streets holding Stalin pictures and chanting "Stalin! Peace! Party! Comecon (Eastern Bloc version of EU) makes us stronger!" and other nonsense while being observed by secret police and party monitors.
Stalin picture was a standard wall ornament in every living room and classroom.