The thing is–and I’m speaking here as someone who does do the later a fair amount–that it really is a different kind of work.
Building up the shallow side man into someone relatable is like applying layers of paint, and usually you’re working with a good set of stencils when you do so. It’s walking over to a receptive-looking smooth blank surface and doing something you’ve been trained to do and have all kinds of models for. You can just start. People do it automatically.
It doesn’t usually even feel like work; it’s like…rolling downhill.
Rethinking the female characters designed as objects, or intended as actual characters but with all kinds of misogyny baked in, is a vastly more complicated process.
First of all, and this is a huge barrier, you generally have to get past your own feelings of repulsion. They might be strong ones about how dehumanized her whole canon design makes you feel by association, or subtle ones about how viciously passive-aggressive all her dialogue is, or a sense of personal anxiety or shame about being judged for wanting to spotlight her and preparing to defend this choice, or anything, but it tends to be there. That turns the project into walking uphill right from the get-go.
The surface you’re decorating here is much less smooth and firm. The mortar is flaking, or it’s already painted with a hydrophobic texture that makes liquid paints tend to run and drip rather than adhering, and of course it’s covered in inconvenient holes and protrusions that draw the eye and will intrude themselves into whatever art you put on top.
And then you have to think about it, the art you’re composing, because you aren’t being handed the scripts you need for this, most of the time. You do not have a robust stencil set to address this need, and when you try to apply ones from the other set it often turns out awkward and blurred, because the wall you’re painting has all those bumps and dips so you can’t press the stencil flat.
There are stencil sets shaped for this, though they may only be usable if you do some masonry work first in some cases, but anyway they usually don’t match the project goals, and if you do give in and use them even though they’re not really what you were going for you’re liable to wind up feeling almost as alienated from your own art as you did from what you were seeking to amend, so it was all for nothing.
So to get the same level of comfortable ownership and sense of depth and desired themes out of a majority of the shallow caricature women that people do out of the bland background men, it generally requires two to ten times the mental effort, much of it spent in a negative emotional state as one confronts the factors causing this woman to be difficult to empathize with, digs under what’s there, and brings out what could be.
And after all of that, you know perfectly well the whole time, a minority of the fandom will even be willing to care, and the odds of drawing hostility specifically for presenting this person in a good light are generally much higher. (This also means you’re more likely to have spent the whole work process in isolation, incidentally, rather than in the cheerful glow of group-brainstorming.)
And because this is a hobby people do in their free time, often specifically for self-soothing purposes, of course the easy version with more community and positive feedback waiting at the end is what most of us go for.
It’s like, when you get home from work and you can either have a microwave burrito or start chopping the whole vegetables in your crisper, some of which are kind of old, to make a salad. Most people don’t have it in them to go for the salad most days, and I can’t really blame them.