Somebody who has spent 60 years working towards a goal just may have done all his "growing" already. Portraying this guy at his time of life as essentially an insecure twenty-something was insulting to the audience's intelligence.
If they had to have "character growth" it could have been handled via flashback. Five minutes of flashback showing Aragorns's life would have given plenty of room for character development.
I agree with Sherman Logan: a character can be fully developed - in the sense that the audience (or reader) knows what he is like, his values, his probable responses to a situation - without needing “to develop” or change significantly in the course of a work of narrative art.
Look at some of your great movie characters: General Patton, John Wayne as (fill in character ;-), Major Whittlesey in “The Lost Battalion.” They are fully realized characters in their context, which is a combat-based context just as LOTR is. They don’t need growth because they have grown already.