Leiji’s art style is a deliberate choice. He has chosen to depict women a certain way, and to depict men another way. Those choices can be criticized, just as any other creative choice in the film can be criticized. Just compare the female characters to the men.
Tetsuro, the conductor, Antares, Count Mecha, none of these characters are designed to be sexy (and they all have very different body types). Captain Harlock is, maybe, but he never takes off his clothes in the movie, and isn’t presented as a sexual object. He’s instead a character that Tetsuro (and the audience) identify with.
Meanwhile, Maetel, Emeraldas, Claire, Shadow, Tetsuro’s mom, the woman with Count Mecha, all of these characters have basically the exact same body type, which just so happens to be what is considered conventionally attractive. They’re all tall and slim. Many of them also wear revealing clothing, or are shown naked onscreen. The only two female characters that don’t fit this model are the old lady you mentioned, and Maetel’s mother, who are both presented primarily as mothers and aren’t sexualized.
Oh, I have a partial degree in this, so I’ve barely cracked open my toolkit. The criticisms I’ve shared so far are very basic surface-level observations. The Bechdel test is child’s play when it comes to feminist analysis of films. I don’t have the time to really get into it with this film (and also don’t care enough about this film to really criticize it), but there’s so much more that can be said about its depiction of women.
The problem with sexist films is not that one film makes these decisions. It’s that many films do. If this one film were viewed in a vacuum, these problems would simply be one person’s creative choices, but the thing is, we don’t live in a world where these things exist in vacuums. People project their own cultural baggage onto their creative work, which is how you get filmmakers making the same fumbles, repeatedly.
We all have our blind spots. Men often aren’t good judges of what is sexist, just as white people often aren’t good judges of what is racist. It’s a lot easier to ignore a stereotypical depiction when it doesn’t affect you personally.
The reason why stereotypes hurt so much is because we repeatedly see them. It’s not one massively hurtful movie, but hundreds or thousands of movies hurting you over and over again in small ways.
Truthfully, most examples of media are problematic in some way. That doesn’t mean they’re all totally unsalvageable garbage! Criticizing something doesn’t mean that it’s horrible and evil and no one should watch it. Pro wrestling is like my favorite thing on earth right now, and I criticize it literally all the time.
When countless numbers of women are repeatedly observing the same things, over and over again, throughout history, isn’t there a chance that what they’re seeing might in fact be real?
The original Harlock manga (stylized as Herlock on the cover) might be worth reading