I recently read the Beach Blanket villains comic where they had a load of short stories and one of them was a short character piece with Giganta called "Giganta Strong". It was really good, but it made me wonder why they haven't done more with the character and specifically more with her and WW?
My impression is that she's been a bit in the wilderness for while. In the New 52 she was a minor character in the Pandora series, then had a handful of appearances in which WW knocks her out in one punch. They seem to push her as the willing minion of every supervillain group and the most developed arcs with her have been redemption stories where she joins the heroes. I did read one comic panel where Steve Trevor has a little chat with her whilst shes in prison, but that's about it.
Which is a bit odd considering shes meant to be one of WW main villains? Plus she has been quite prominent in some of the cartoons like the old Justice League one. You would think that's more than enough incentive to work the character into a story with WW. I say that because, both the Steve bit and the Beach Blanket story do look at how Giganta feels about WW. But that's a moot point if she isn't in a WW comic and the Amazon doesn't have anything to do with this villain. To take an extreme example, the story with Mr Freeze isn't something in isolation, how the hero deals with and interacts with this morally grey villain is relevant to the story and arguably more important.
If I had to speculate I think the main issue they have is that they want to focus on the fact that WW is this Olympian Goddess who is a top tier superhero who can go toe to toe with the likes of Darkseid. Cheetah is possessed by a deity, Circe has magic, Ares is literally a God; then you have a 50 foot woman. Bit of a power imbalance. All the others fit snugly in Wonder Womans league. You imply WW isn't that powerful if Giganta is a threat to her. The likes of Dr psycho get around this because they are using subversive powers and abilities; but with Giganta its a question of outright strength. Hence getting one punched all the time.
As I said, I quite liked the light hearted depiction of Giganta they had in the "Giganta Strong" short story. I am not saying they should make her grimdark or anything like that. But I do think it would be nice if the character had a solo outing in a WW comic, if she did something beyond a supervillain teamup and if they established some kind of character dynamic or conflict between Giganta and WW.