It is a profoundly moving moment: a fragile but steely 65-year-old woman, banished from sight for 15 of the last 21 years, emerges smiling into the light, surrounded by cheering supporters. She wears a flower in her hair. Aung San Suu Kyi is free at last. Those who have campaigned for her release, including many western governments, have cause to celebrate. But this is not yet a defining moment in Burmese history, let alone the "Mandela moment" some believe they see.