A lot of people seem to miss the point here entirely. I find that the joke loses some steam because people take it too seriously, and there actually are nerds who try and treat this as a serious issue, largely because they feel that by speaking against fantasy artwork it will make them more appealing to women.
It's important to understand that through most of history women were second class citizens at best for a number of reasons. It's not just a lack of physical strength but also relative vulnerability compared to men. See, women have these things called "breasts" which are very sensitive. A girl gets slammed in that area, and the closest analogy for you gentlemen would be to getting kicked in the nuts.... and the size of the breasts in question doesn't paticularly matter here.
It's relevent to this discussion because what this means is that your "sensibly armored" female warrior is going to be totally ineffective in things like plate or chain mail. A blow to the chest which a guy in a breastplate would shrug off is going to take a lady out of the fight instantly.
You might be thinking "well, then how did women fight historically..." and the answer to that is that they didn't. There are rare exceptions of course, like Joan Of Arc, but in most cases such women were as much a political prescence as they were actually effective on the battlefield in a personal sense, and again your dealing with rare individuals, an exception, rather than the rule.
Now, in the course of fantasy there has been a tendency to want to portray a bit more equality. Ignoring things like how women simply can't reach the same physical peaks as men, and how they are always going to "underperform" at the high end assuming people who take fighting seriously and reach their peak. ESPN did a thing many years ago where there was some lady who was ranked like #2 in the world for women's martial arts who wanted to go cross gender, she got pitted against a guy who was like #30 on the men's side or something and after all the hype he pretty much just played with her... athletics are segregated because it's not a small differance. Still in fantasy when you ignore this and are playing "what if"
it raises questions about what a female medieval warrior might look like.
A lot of the fantasy artists responsible for the looks like the "chain mail bikini" and "brass link bra" were operating from the perspective that anatomically your not going to be able to armor a girl for melee combat. The key problem of course being the breasts, the area being too big and central to the motions needed to really armor the way a guy's soft spot can be protected with a cup. You try and build a "cup" around the breasts it's going to either be huge and cumbersome, or not be able to deal with the impact in question.
Women today who do fighting and athletics tend to use things like Gis, spandex, leotards, etc... the same as men. However in ancient europe such fabrics didn't exist. The comment about "mobility" becomes very valid as your looking at someone whose only potential combat strategy is going to be able to move out of the way, and the anatomy being what it is the lady in question is going to want support. The "Plate Mail Halter Top" isn't going to protect in a fight much, but it will at least prevent the skin from being split open if she takes a shot to the chest and for whatever reason the enemy doesn't finish the fight.
I point this out because I've actually read some things about it. One thing to remember is that a lot of the early fantasy artists and illustrators... like say Frank Frazetta who famously did artwork for "Conan", were pretty heavily into athletics and such themselves and were pretty much told "this is what you need to do a picture of" and they improvised, using what was actually a fairly surprising amount of common sense.
The thing is the tendency for people to go "OMG, a half naked lady! exploitation!" when really I think this is less of an issue than you might think. Especially seeing as female artists like Julie Bell who do this kind of material tend to go in a very similar direction, and if you really stop to think about it, it's pretty obvious why.
A character like Samus Aran, or heck most modern or futuristic action ladies, have the advantage of being from a higher tech level. Guns and tech being the great equalizer, combat is no longer about personal athletic abillity to the same extent. I don't think Samus' armor was ever broken down in how it works, but in fiction such armor suits include things like anti-kinetic gel layers in the armor, built in dampening fields, and other things. Basically a suit of super battle armor that is going to be able to bounce bullets fired off an electromagnetic rail off it's chest (well at least for a while) without splattering the person inside due to the impact is going to render the sensitivity of the chest area kind of a moot point by definition. When it comes to things like cyberpunk, questions can be raised as to why a lot of the women dress the way they do, but at the same time you can ask why women dress the same way IRL.... or why fantasy novels written by women largely for women (like Kim Harrison's "The Hollows") are probably WORSE in the way they have the women dressing than the stuff guys come up with.
I understand the joke is from College Humor, but it's old, and truthfully I'm kind of tired of it. I've been defending fantasy, and fantasy art for many years now.
My typical response is to challenge a lot of the critics to actually come up with a mode of dress that would be more functional than what some of these ladies are wearing. In some cases when the costumes are admittedly obnoxious (it does happen) that's easy, in other cases not so much. Like it or not a leather skirt, knee boots, and halter top is a fairly practical costume for this kind of action. Even the question of "why a skirt, when everyone else is wearing pants" is fairly easy to answer... try doing a full split in a pair of pants if your capable of one. Gymnists don't wear regular pants when doing their thing for a reason, they are going to get torn out fairly easily. One thing girls have on guys is that they can do splits and a lot of flexibility based moves a lot more easily than guys can and with less practice/training, you can see the differances in men and women's gymnastics for example. A skirt is going to be more condusive in many (but not all) cases to a woman's full range of movement in the situations she's going into. When you look at the stereotypical female rogues and such who wear those costumes... they are exactly the kinds of characters who would be thinking that way, which is probably why a lot of the artists drew them that way to begin with.
Of course in more eastern flavored fantasy where silk is more readily availible at the generic "ancient level", that presents other wardrobe options for both genders that tend to go beyond the points being made above... but that's usually not the kind of setting being dealt with.
