Both openings "fit" for the seasons they were used. I have to say that if they hadn't changed the opening, the first opening would have seemed out-of-place for season 4 and 5 as those seasons move away from the themes of 1-3.
I found your comment about season 4 being named the coming of age episode interesting as I've always thought season 3 is where they come of age and season 4 is about hitting their stride in the next stage of their lives.