I missed your articles greatly.
That said, I'd probably agree that the biggest problem was the fact that the victims were willing. To demonstrate...the cartoon Johnny Bravo (though lacking sexual overtones) is funny PRECISELY because he always struts around ladies, flexes his pecks and calls them names that are just hilariously lame in this day and age...and the girls ALWAYS give him a beating for it. That's what makes that type of relentless mysogony (light though it may be) funny - because you can certainly see women in this day and age reacting the same way (and not necessarily because he got what he deserved for all of you hypersensitive types that feel the need to think JUSTICE! at this point - Johnny Bravo is just genuinely clueless to the fact that the times have moved on from when this sort of approach was actually considered bold, something he and Duke Nukem most definitely share in spades). There is an even more awesome episode, however, about how Johnny Bravo's mysogony is at least honest and really is nothing compared to the lying sleazes that regularly successfully pick up babes but...that's getting off topic now.
The point being...that's the problem here really. It's not that Duke should be a different person - hell no! Duke should always be the Duke. The problem is that the game world, in which he finds himself, hasn't moved on without him. If he managed to stick to his guns to the end of the game through the adversity of modern sensibilities constantly trying to change who he is...then sure I might actually have a bit more interest. Because like it or not, that is the tale of a hero making it to the end in spite of the world telling him he's passe. And wether you agree with his style or not, it would actually make Duke a true old-skool hero again!
Unfortunately, by all accounts, the writers and game designers didn't have the savvy to think of doing something like this to surprise their audience with it. And instead we just got a mysogynistic fantasy land that really holds little long-lasting appeal. A shame really, because I'd probably like a story of someone, who is at the very least completely honest about himself, making it through to the end in spite of the many politically correct hypocrites that try to dissuade him from his path.
TL;DR It's not what Duke does during the game that's offensive. It's how the characters within the game react to his actions that is offensive by deliberately overestimating the audience's suspension of disbelief.