When it comes to the companies profiting the most, the illustrators are drawing a style dictated by their higher-ups, who make those decisions based on what their marketing team tells them will make the most money. The question, really, is: why, in our culture, must depictions of female combatants (superheroes, mages, warriors, whatever) be sexualized in order for them to be the most popular/profitable? Sure, one
could look into niche markets to find female characters where who they are has less to do with their looks and more to do with their skills and other parts of their personality, but it's disheartening to have to dig for these characters while they're overshadowed by their physically endowed counterparts. With male characters, sure, some of them are sexualized one way or the other; but, most of them get a few sentences of description, an illustration or two with modest yet unique features and wardrobe, and then they let their actions and personality speak for themselves.
One frustrating trope that comes to mind is that when there actually
is a competent-yet-modest female character, attention is drawn to that fact as if in fascination. Whether this is commentary of our own culture on the part of the author, or a subconscious march in lock-step with that same culture, it still stinks
Long story short, picture 1 looks like cosplay and picture 2 looks like a serious warrior because of the feedback loop between our culture seeing them as such, and the producers of these fictional characters giving us what we want, and that situation is maybe undesirable.