If you watch or see something often enough you get use to it, so seeing paintings of prominent kings that are wearing powdered wigs (perukes), or TV programs in which barristers with those British accents have on powdered wigs, you just take it for granted that these things exist. However, in a time of reflection, you may ask why? After all, kings are important people, a court of justice is typically a somewhat solemn and serious affair, yet prominent people within these institutions are wearing wigs that rather than making them look dignified, appear just a little ridiculous.
Apparently, in the 16th century, which was far before the age of penicillin or antibiotics, London was suffering under an epidemic of syphilis, in which one of the side effects of syphilis was a patchy loss of hair. Another, more important reason for wigs, was that head lice was a common problem in those times so that by shaving one's head, and then adding a wig onto the top of your head, you could take care of the problem of head lice and have an acceptable or even fashionable accessory to wear. Then, of course, there are some people whom suffer from premature balding or graying, in which for vanity purposes they preferred to wear an elaborate wig. So powdered wigs served both a practical use and were also de rigueur in those times. What is somewhat incredible, however, is that powdered wigs are still used in a court of law in most Commonwealth countries till the present age.
The current usage of powdered wigs is best looked upon as a symbol that those that wear these wigs belong to an exclusive club or guild, in which commoners aren't permitted to wear things of this sort. The powdered wigs are a bit ridiculous on purpose, because they are not worn for everyday walking or strolling through the streets but to designate the wearer as an important erudite and educated person of some prominence and to identify themselves one to another. This means that those that wear powdered wigs will, almost by nature, even if on opposing sides of a political or judicial matter, treat each other with a bit more respect and deference than they would if they didn't wear this symbolic emblem on their heads.
Perhaps powdered wigs will be consigned to the dustbin of history in the near future, as, after all, there isn't any necessity for the wearing of them, but I suspect those that wear them have no real interest or intention of seeing this occur, as powdered wigs are an important status symbol in which in this day and age, most status symbols can be copied or imitated by others who have achieved little or nothing. To wear today's powder wig you must essentially be a barrister, judge, or a member of parliament commemorating a special occasion, this therefore gives you a status in which it is clear that you are a person of some importance, of some worth, and of some respect.