I still, after 12 years since I first saw these kind of works, can't understand this fetish.
The power? The giantess being able to dominate everything around here. Think femdom + kaiju; the more simple 'just a giant woman' pics are simply because there's more woman. Like an exaggeration on the tall girls/thicc girls interests.
Someone else could probably give a better explanation.
Actual Macrophile here, and there's a multitude of possible ways different people take this fetish. Obviously they all have different tastes within it, and fetishes aren't all that logical to begin with.
Like, some of us are all about a larger than life woman having ultimate power while others are about about gentle love with size differences and yet others are just about giant feet and what more. There are many ways to be a macrophile (or part of any fetish).
Ultimately fetishes are mostly a thing one has, or doesn't get. They mostly only make sense to those that have them.
--------------------
That aside.
This pic definitely leans into destruction and feet, which isn't ideal for me as I'm not super huge on the destruction part and don't have a foot fetish.
Ah well hope I helped some people with this comment.
I still, after 12 years since I first saw these kind of works, can't understand this fetish.
As a size artist myself, and one with preference for destructive type of drawings, I feel it's my duty to tell you what's behind these pics.
In size art there are many types of drawings: gentle and violent ones, in which you can add many other fetishes such as sub/dom, insertion, unbirth, vore, etc. What I mostly draw are gentle and destructive ones.
What I enjoy most of these kind of pictures were a giant girl is kaiju sized and destroying stuff is how casually she is doing so much damage with her body that seems kinda effortless. It's like a matter of power showoff without even trying, and enjoying it, that makes it better (this picture literally). Sometimes destruction of stuff happens without the giant girl even is aware of it, which sometimes makes it even better, like walking through some street and suddenly steps on a car and she barely felt it cause of how big the girl is. And when they are several hundred meters of size, they basically turns into walking natural disasters (I am currently working on a comic exploring this size).
In summary, the destructive pics of size art, what makes it enjoyable, is how much destruction causes the mundane actions of the giant girl over her out-of-scale world WITH HER BODY. It is such a buzzkill to see a giant girl using powers and lasers that causes mass destruction instead of using the size factor for leveling down everything. The key is the physical contact and impact the giant girl has with the tiny world that makes it more appealing and fascinating.
And as an artist, I must say that drawing size art is damn challenging since you have to deal with a lot of perspective work, scaling down objects for reflecting the size difference of the girl and figuring out how to make the pic look interesting, fun or enjoyable for the viewer. It goes way beyond drawing a city and then placing a giant girl in there. That's boring and lame. The contact and interaction is what makes it enjoyable.
Regarding the gentle part of this fetish, is more about how the tiny guy/girl is basically dominated/controlled by the bigger girl with mundane actions, like pinning down the tiny with a mere finger, licking him or, as some foot lover people loves to see, how a foot, the size of a truck, pins them down. It's more of what they love over them. Personally, I like when the girl is playing with the tiny using her boobs. Some people prefers the normal size girl and tiny guy/girl over a giantess scenario cause of how private it is in eyes of the world and intimate. You can also have body exploration scenarios with the gentle part of this fetish which is quite neat, fun and interesting imo.
In between you can dump many other kind of fetishes such as vore, odor, scat, etc, but I'm not that into them as for drawing them (except for a slight of vore).
I hope this helped a little more understanding this fetish.