Having the abstract mannequin as a default may make people feel like they might as well just buy one of those wooden posing dolls (https://www.amazon.com/wooden-mannequin/s?k=wooden+mannequin).
[1] https://www.clipstudio.net/en/characterart/#:~:text=Learn%20...
That is the most important feature this would make me use this over the good old wooden puppet, which is small (10cm). I.e. it travels with me with my drawing utensils.
I guess I am asking: what exactly is the value proposition?
Imagine a character walking with forward kinematics. Every time you move the characters hips , you’d have to rotate the leg joints and make sure the foot doesn’t slide. Remember virtual characters don’t have friction.
IK lets you lock the foot in a spot so you can animate the body above it without having to spend time matching the foot position.
In a real world, this is like if you tried to put your hand on a door handle while jumping up and down. It’s easier to keep position when you hold the handle than if you were to just touch it.
You need a proper motion controller on top to actually have realistic walking motion driven by steps.
INVERSE kinematics derive joint angles from coordinates
it's useful when you have a chain of joints and a mug to grab with it
If you're comfortable enough with 3D meshes to make use of the 3D export function in the paid subscription, you could just download a manekin into Blender and do all this for free.