4 and 5 both kept Michael Myers operating in a recognizable way. His efforts centered around a primary target, but he continued to do things the way he previously had...basically by killing everyone in their orbit. What he did in 4 and 5 was virtually the same as what he did in 2. He'd kill a variety of targets....some for practical reasons...others less so. Some people complain about giving him the 'family' oriented motive, but since his MO remained so much the same, I could accept it. You could argue that killing randomly was better, but they made this approach work quite well, in its' own right. However, in 6, they chose to introduce the cult, and this changed the entire dynamic.