The obvious Real World answer lies in the nature of males. (Need I explain further?)
In the fantasy settings of D&D ...
It was every fighter's dream to have magical armor in 1E, because it was weightless (literally: weightless.) It is nice not to have to carry around 70 pounds of plate armor and shield ... just wearing the stuff is difficult enough (use some Real World comparisons.)
Nobody in 1E ever really figured out (not in any supplement I ever saw) how to produce Force Field Clothing, which is what a chainmail bikini would be a variant of (for men, simply, shorts.) The equivalent, roughly, of the Dune personal body shield. It never happened.
Theoretically, Wall of Force, cast multiple times and with Permanency (5% chance per application of a permanent loss of 1 point of Constitution) could have been used to create an almost invincible set of shields around the user, using tiny pieces of clothing as their focus, moving with the wielder (an exception to the normally stationary nature of Wall of Force.) This would have granted AC -10 in 1E or 2E, AC 30 (or higher) in 3E, and gave at least +4 to saves against spells like fireball and the like. (Maybe, +8, if really done right ... or count it as 90% cover.)
Considering just how BADLY any sort of clothing was vulnerable to fire, it was a worthwhile endeavor. Fire was an incredibly popular weapon back then ('I carry 50 oil flasks, and the wizard is ready with Firefinger!') and Item Saving Throws were required if you failed yours. If they failed, you were alight and took 2d6 damage per round until it was extinguished.
In a Worst Case Scenario, Armor - made of metal - could fail it's save, and aside from being ruined, it could superheat and glow from that heat. Or, even partially melt. Anyone caught inside a full suit of Armor, even Mail, when that happened was fried (2d6 damage to 5d6 damage per round from the incredible heat, plus 2d6 regular fire damage from burning clothing, save for all other items again) unless they could jump into the nearest (hopefully) large lake.
LOL. The Dragon thus got it's meal Well Done, before the wrapping was even removed.
Protecting clothing and armor from this effect was extremely difficult. It was far easier to protect the person. So the less clothing or armor you wore, the better. Rings of Protection were thus quite popular. Spells like Phantom Armor and Spirit Armor were equally popular.
The Chainmail Bikini actually, thus, made sense ... within the reality of 1E, and especially in 2E, where armor did weigh (although it still carried no encumbrance penalty.)
You would have thought that the Chainmail Bikini of Force, of the Chainmail Bikini +5, would have been devised. But it never happened.