Well, I studied the civil rights movement in history last year, so while I'm not an expert, I do know what I'm talking about. I believe that he was important as he provided a focal point and raised morale and support; for a cause like that, you need an identifiable leader, someone who people can look at as an example - through being a focal point, he was important as a unifying force and as a public figure.
However, he wasn't the only important person - people like Thurgood Marshall and Ella Baker also played a massive role. Change doesn't happen with just one person. You also need the grassroots movement, the ordinary people who take part in the bus boycott or the march to washington - it would have been nothing without the grassroots support. Or in fact the presidential support - JFK and Johnson were instrumental in getting the legislation through (due to a certain extent to JFKs assassination)
So in conclusion, yes he was important, but you can't underestimate the role of the other people involved in the movement.