It is fascinating how often this subject comes up although this time someone has worked a women's lib angle into the discussion. Underwear (or intimate apparel as it is coyly referred to in America) is a fairly recent innovation for women's clothing as it only appeared in the 19th century although men had worn underpants prior to this. As to going "regimental", while this seems to appeal to certain individuals, from a purely practical point of view the cost and inconvenience of frequent dry-cleaning in order to maintain an acceptable standard of hygiene would surely weigh heavily against it.