Sorry, but that was exactly your point. Maybe you worded it poorly and meant to say something else, but you were specifically responding to the eva criticism by citing a historical reference. Historical reference you are apparently not very knowledgeable about if you think how spies dressed is some great mystery, but your comment is essentially a non-sequitor if you weren't trying to defend Eva from design criticism on historical basis.
As for the rest of your post....
I think most people would agree that Eva's visual design is better suited for her role in the story in a pulpy way, but it's not really Eva herself that's being criticized, it's Kojima. Any argument of artistic integrity loses water when you realize that he would have sexually objectified her whether she was a seductive spy, a plain scientist, a sniper in the arctic, a military freedom fighter, or even a traumatized child soldier. Sexualizing women to such an extent that it effectively objectifies them is just what Kojima does in his games. Eva sexualization fitting her role in MGS3 comes off, at best, a fortunate coincidence.
And even then, it's not like the seductive spy is a trope that HAS to be played in this way. It would actually be far more interesting and intimate if she had seduced Snake not by constantly flaunting her body at him, but by specifically creating an artificial personality that, for him personally, was attractive in a deeper emotional way. If anything, she comes across as desperate and bordering on incompetent as a seductress when Snake is consistently disinterested whenever she gets half naked to no effect. Snake gets involved with her when they've completed the mission, becoming comrades in arms, and she should have picked up on that being the key to his heart, dropped the sex kitten act, and angled for that way earlier.
But then the player wouldn't have been to oogle her as much, would they? That's the REAL reason she's designed like that.