As a Sikh (convert, of northern European stock) I'd like to add a bit to this discussion. Our appearance owes a lot to the Muslim oppression during the reign of Aurangzeb (Mughal dynasty). In the early days there was no requirement to wear or carry anything. Sikhs were just people who followed (or tried to) the teachings that originated with the pragmatist Guru (teacher) Nanak, a Brahmin-born present day Pakistani. These three teachings are honest, hard daily work, sharing of its fruits, and meditation on God (and, importantly, there are many paths to God, not just ours, or one). It should be noted that our God, my God, has quite distinct connotations and shouldn't be (mis)understood within the Abrahmic lens (specifically with regards to non-duality; i.e. our “understanding” of God isn't as some entity wholly separate from us, and certainly not something to be feared).
Aurangzeb was a real prick. In disgusting contradiction to his father (or grandfather) Akbar, Aurangzeb alienated the Hindu elite and started Islamifying his territory. You know, something like the Taliban. He did this because he believed Mughal decline was related to their not being Muslim enough. The usual BS of forcing people to convert or be slaughtered was the rule of the day. Long story short, one of the things he dictated was that only Muslims could wear turbans. Guru Gobind Singh, whose father was beheaded for not converting to Islam (his two young sons also martyred), said enough was enough. As an “in your fucking face” move he said that all his Sikhs, the Khalsa, would wear the turban and everything else. It's a uniform. It supports us in our desire to adhere to our code of conduct, and it told the Muslims they were going to have to fight, or give up their oppressive ways. They fought. If you didn't know, the Sikhs eventually took over Pakistan and Afghanistan and ruled for a bit. I think what brought down that empire was the British and their fear of a Sikh-Gorkha alliance...
We wear the turban to stand out so as to induce fear in an enemy and comfort those who we will protect (even those who don't like us because of our hairy faces, funny “hat”, or whatever). We wear the steel bangle as a symbol of our courage and to remind us to behave righteously. We wear “loose fitting shorts”, or regular underwear these days, out of a sense of modesty (as opposed to the naked or half-naked sadhus that run around India). We don't cut our hair because that was the way we were created, or evolved, if you prefer. And we carry the kirpan (lit. the hand of mercy) and/or any other weapon in case we are called to protect society from some “evil”. In observing this tradition on the whole we can't hide from our only ritual and primary calling: “sewa”, or self-less service to humanity.
As a rule, Sikhs don't want to fight. We want to work hard, serve society (without making any distinctions in regards to religion or gender or anything else—all are equal), and lead a spiritual life. But, if some oppressive force (historically Islam for the most part) moves in and refuses to even tolerate other beliefs, doing so in a violent way, then, after ALL peaceful means have been exhausted, violence on the part of Sikhs becomes obligatory (to protect Sikhs, Muslims, Hindus, Buddhists, Christians, atheists, satanists, everyone not being an intolerant shithead). The pacifists paradox (e.g. what to do about cases like Hitler, Pol Pot, etc.) is, in theory, nonexistent in Sikhism.
Sikhism, if you ask me, is also American as apple pie. We want to participate in an interdependent society (note the symbolic nature of clean and combed hair—that has spiritual value in itself—distinguishing us from the Hindu, Jain, and Buddhist renunciates), and respect, as opposed to merely tolerating, other peoples beliefs.