This. The mohawk means so much more than just "looking cool" i.e Apocalypse. It's symbolic of some of the most character defining moments in Storm's history. Marking the beginning of an arc where Storm now seasoned and grizzled, having fought various enemies that challenge her ideals and morality, wiling to put her life on the line to save Kitty from Callisto/Morlocks -- sees the world through very different eyes than when she was introduced. No longer is she as naive and wet behind the ears, wanting to see the good in people. She now knows the ugly truth and the mohawk is representative of Storm's mindset and darker outlook on the world at this point in her life. And of course, she lost her powers and still kicked ass as the leader of the X-Men cementing her place as one of the greatest Marvel characters of all time. A very emotional arc for Ororo and just proves why proper character development is vital to becoming invested in whatever character's given journey that the writer has presented to the audience.
If my short stint in film school taught me anything about storytelling, it's that character development is essential to building a well-rounded character that your audience can connect with. Claremont was a master at this form of arc buiilding with the X-Men's characters. It will be nice to have X-Men movies where Wolverine and Charles aren't the only ones who end the movie in a different place than where they began.