It's pretty much standard for any man in any priestly order in my jurisdiction to wear at least a cassock when on "church business." That being said I can see the point of the priest wearing a cassock or collar when on "church business." But seriously a man isn't defined by his attire. While the cleric is set aside with his attire he isn't less of a cleric if he shops at the Kroger in a rugby shirt and jeans. I guess there are two sides to this debate. One is that a priest/deacon etc.. should always represent his office and be in clerics when about in public to witness, that is, he is set aside (read the prayer of blessing of the cassock) in as much as the cassock/black is to make him "invisible." But at the same time he should always be who he has become through ordination and the clerics help remind him that and those around him that he has been chosen to be the leader of the flock. The other argument may be that a priest/deacon/bishop should be able to melt into his surroundings in non-clerics and enjoy his peace. It's a conundrum. The middle ground seems to be the short bearded short hair and roman collar. Still that sets aside the cleric from the laity.
As usual it is up to the cleric's bishop as to what he is allowed to wear and when. I know some dioceses only allow priests and deacons to wear a cassock when on church property or say at the hospital visiting the sick. Some priests and deacons aren't allowed to wear clerical hats nor are they allowed to have long hair and may have to receive permission from their bishop to wear facial hair. Then you have some bishops that allow long hair, skufias, exoriasso or a basic cassock to be worn in public when no on church business. The question is, if lay folk are never to be on a constant path of theosis and the priestly orders are chosen to be set aside to help guide the laity on the collective path of theosis why not allow a cleric to dress as such at all times. If the laity aren't to forget about prayer and church life why, their leaders are always on duty as well. And that may include assuming wearing the clothes they were set aside in (cassock, exoriasso, skufous)...
I guess what maybe the point here in this whole thread is that seeing your priest out and about in a woolrich shirt and khakis may shock you, but that doesn't mean he should be judged for it. Priests, deacons and Bishops are people too. They have families, they have fears, they have joy, they have bills to pay, they have interests and hobbies. That is often something people forget. Being a priest, deacon or Bishop doesn't make a man not a man, it poses him as a leader within the community. But a leader should not be judged by what he wears, only God judges.
After all do we not pray in the Divine Liturgy that the bishop "may rightfully divide the Word of Truth?"
That includes making sure from his priests, his local representatives, his deacons, his subdeacons, his readers, his flock are being taught the "Deposit of Faith" correctly. As we know the Orthodox Church, the Christian church is a collection of local churches united by the Eucharist AND the Deposit of Faith.
We are not unified by priests wearing cassocks in public. We are not united by a singular man in one city. We are not united by all the small traditions that are sometimes externals (such as the priests wearing riassa in public). Orthodoxy is completed at the altar not by the length or a man's beard, the size of a woman's headscarf, how many prostrations we do or how many prayers we say. Those things may help someone keep on the theosis path. Remember, the most important thing is Theosis, the Deposit of Faith that directs us and of course the number one unifier is Christ in the Eucharist.