No reason except perhaps in certain sporting activity's in order to keep thing tucked away safely
It's against the Ordinance for the men to wear underwear.
Wearing underwear is not a strict necessity for men, but it is generally recommended for hygiene and comfort reasons. Underwear provides support and protection for the genitals, helps absorb sweat, and prevents chafing. However, some men may choose not to wear underwear for personal preference or cultural reasons. Ultimately, the decision to wear underwear is a personal choice based on individual comfort and needs.
Men have many styles of underwear. They include bikinis, boxer briefs, briefs, boxers, and long johns. The style you choose to wear depends on the amount of support or freedom you prefer.
Men and women wear underwear so as to preserve or keep their private parts private.
Most of the overall population has the idea that they HAVE to wear underwear to be normal, but in reality underwear is only a recent invention, and because most people shower regularly there is no real need for it in these modern times. Most men "go commando" from time to time; some men never wear underwear. It is mostly a matter of comfort and support. I prefer freeballing because I enjoy the freedom associated with it.
at that time they did not have them for men so no
none
No. Men and women wear underwear to bed all the time and nothing bad happens to them.
Some men don't wear underwear because they feel it is restricting. There is also concern that the friction and additional heat can reduce sperm count.
For women it is for privacy, I mean we all probobally know about skirts flying up in the wind or nosy posy men, so for lady's safety wear underwear. For men it is because men need to be sanitary, and so they wear underwear to keep other parts of there body clean.
Gay men wear the same kinds of underwear as straight men.
If trying a bathing suit on, definitely yes. Otherwise it depends on the suit and your level of modesty. Most men's suits have a mesh "undergarment" and women's suits are designed to wear without underwear.