It's kinda about the medium, I assume the movie worked fine as the biography book it was based on, it probably also worked fine as a audio play or radio drama, but as the mediums show imagery, that's where the story, regardless of the message, will risk being used as titillation. From what I've heard about the movie, it has its story in the right place but the decision the turn it into a film is inherently flawed.
That being said medium is not an issue with gal-gun, the problem with gal-gun is the point of the game, and unlike with say, Zanki Zero, where UNDERAGE nudity can be edited out and not effect the end product, I think it would be fair to say games like gal-gun don't have that luxury... it's just... too... problematic... if you'll accept that terminology.