When it comes to Gur-baani, u can hide it from the world if u want to.
U can do ur gurbani in ur surti or in closed room.
But when u wear Gur-baanaaaa, u announce it to the entire world that
you are a member of Khalsa Fauj. It takes LOTS OF COURAGE to wear baana expecially
in the 18th and first half of 19th century. When the Britihers caputred Punjab, they killed almost every warrior Nihang as they knew that these BLUE BAANAA WEARING SIKHS ARE THE TOPMOST WARRIORS OF THE SIKH FAITH.
Amritdharis who wear Baanaa and load their body with Shastars, wear a uchaa dumalla,
Akal Purakh tells them lots of things during their simran abhiyaas, which other amritdharis dont get to know.