Spellcaster? monk? or possibly just her day off? She's obviously not adventuring right now, she's sitting around in comfortable clothes, a time when many people do wear less than they would in public, especially less than they do "on the job" as it were, this would be the "verisimilitude" and "appropriate" part, and it doesn't prevent her from kicking butt at a later date.
Ah, yes, exactly what I want from my gaming art, pictures of people taking days off.

Even spellcasters and monks have tools of their trade (wands or scrolls or kama or simply even backpacks or clothes that don't look like underpants), and even then they'd usually be doing things other than eating berries suggestively.
I don't think verisimilitude is the
point with this picture, at all. If it is, the picture is incredibly lacking. The point, if I apprehend it, is "sexy forest woman." It achieves that goal pretty well, but if the goal is "a realistic adventuring woman," then it is full of fail. She doesn't look like she's on any sort of adventure. Even you agree that she's on her "day off." That's not the kind of thing I want my adventurers really depicted doing. It doesn't make me want to play the character. Unlike Klaus's sexy stabbitty-druid, whom I could easily see taking on some goblins and shouting battle cries amongst the gore.
Redhead, Redhead's do not tan.
Untrue, but even if she matched that stereotype, she'd be covered in freckles, no? Or perhaps just scars and blisters from constant sunburn? Because she certainly doesn't wear clothes that protect her from the sun!
she looks a bit dusty to me actually, if you mean no blemishes, then yeah, she's hot, I never said this was a bad thing, but she does look slightly unkept (the hair, and a bit of dust), she does look like she's been outdoors. (although she may well be wearing makeup on her face)
Have you ever walked barefoot in the woods before? Her feet should be disgustingly brown-black, her skin darkened from mud, barks and twigs stuck in her hair and her fur bikini, her shins covered in cuts and scrapes.....realistic, this isn't. This is "I just got out of the shower and now I'm going to seduce you by eating berries."
That, or they're just fur.
Sure, but for someone prone to sunburn, they're not covering much, and they still look very flimsy. They're not good forest wear -- anyone would tell you to wear long pants and long sleeves to protect your skin; gloves if you could, and you're climbing trees. It's just not practical for her environment.
Which is why I don't think the
point of the picture is to be realistic. It's to be sexy. It achieves that goal. I think Klaus's #1 sets out for and achieves that goal as well, while still looking like a heroic character in a fantasy world. Berry McFurkini achieves that goal, but doesn't really look like a heroic character.
She's sitting in the forest eating some berries, there's nothing seductive about the pose (although the face is a different thing), she looks like a normal attractive woman in a situation where's it's not inappropriate to show skin, she's not submissive or desperate, it's just a day in the life thing, y'know, as opposed to "on the job", when an actual adventurer is going to be wearing work clothes for outside, which generally aren't that flattering, attractive, sure, but not really sexy, or cheesecake, makes it "inappropriate".
A day in the life? She usually tries to tempt people by seductively eating berries? She goes on the job in a furkini? She walks through the forest without getting muddy, bloody, insect-ridden, and trashed? She's obviously being alluring and seductive, but she doesn't look at all like she's on any sort of job an adventurer would do.
She looks like she's on a job a Dryad might do. She's Fey, so she doesn't have to worry about the practical concerns of the forest. She's supposed to be attractive and alluring, so the "come hither and eat of my 'berries'" look is warranted as opposed to nonsense, as is the furkini.
But as a depiction of an adventurer, she sucks. I've never known any PCs of mine or anyone I know to ever sit half-naked in a forest trying to eat berries as suggestively as possible. If you have, it sounds to me kind of like a boring time, so I'm sorry. I have known PC's of mine to look threateningly down at their enemies with their weapons and their allies behind them, like Klaus's #1, so that works for me. That's a half-step away from action and adventure. Berry McFukini isn't.
Klous's #2 pic is a heroine, she's kicking butt and taking names (not that can remember why you take names when you kick butt right now), with #1, I see a model wearing fetish gear based of timeline appropriate armour, which makes her more of a parody of a heroine to me.
If you want to see a wang in the Washington Monument nothing's going to persuade you otherwise, but I'm telling you the Washington Monument isn't about wang. The resemblance, while perhaps not entirely coincidental, is irrelevant, because it's not meant to impregnate anything. Likewise, this gal isn't meaning to put anyone in sexual bondage. She's meaning to stab some gobbos.
She's actually a "fist of the forest" I believe, some sort of monk/druid, that is, the kind of person who hangs around in the forest in unrestrictive clothes, you're right in that she's not looking overly assertive/buttkicking right now, my point is that if your feel the need to show some sexy, you can do it in the down time, or with appropriate characters, in appropriate clothing, (obligatory comment about how D&D isn't just about combat) as opposed to front line fighters, for whom it could be life threatening to show skin "on the job" as it were, especially when the male fighter beside her is wearing the same thing without the holes. (no, not evidenced here, but it will happen if you stick with that kind of armour)
Again, characters in their "downtime" are pretty boring, and aren't really good depictions of realistic characters in the fantasy world. The need to show "some sexy" is always going to be there -- art should be attractive. And in D&D, like in Klaus's #1, it's not necessarily as threatening as you assume (magical armor, magic spells, magic items).
Meanwhile, wearing a furkini in a forest is going to be very threatening, because in short order it will be a ragged mess, you will be covered in cuts, bruises, mud, and bugs, and it won't really protect you from the elements, such as sun, wind, or rain.
And just so you don't misunderstand me, I think both Klaus's picture AND Berry McFurkini are acceptable RPG art. I like the amazon better, because she's a more assertive character, less of a cliche "beautiful woman of the untouched virgin wilderness who sits there and waits for people to come to her seductive gaze," but they're both fine pictures.
I'm just pointing out that if your litmus test is realism, that she fails that test as colossally as Klaus's amazon does, so she's not a good example of your case. In fact, they just seem to be an example of the litmus test actually being "I prefer calm redheads in bikinis to aggressive blonds in armor." Which is fine, but it's a little weird to want RPG books to reflect that desire.