The heathen world scoffs at the idea that women ought not wear pants. But there wouldn't be so many broken marriages and abortions if women clothed themselves properly. The way a woman dresses has a profound impact upon her behavior (1st Timothy 2:9). When I see a woman in a long modest dress, my first impression is that she is a Christian who loves God and righteousness. A woman in pants tells me that morality doesn't mean much to her, and that she doesn't care or understand how the man's mind works. You have no idea ladies of what goes through a man's mind when he sees a woman's buttocks and thighs.
Warning: Rambling about my own man’s mind
To me, women wearing trousers are the default, so they have no special erotic effect to me. Completely neutral.
Skirts and dresses, even long ones, on the other hand, have more potential to be sexy to me. For one, they are not the default, making them more noted. Furthermore, they have more potential to emphasise and exaggerate the hips, which is the curve that is most erotic to me. Finally, um, well, they are the garments that open towards the vulva…
Really, the garments (excluding underwear and actual revealing clothing) that are erotic to me are medium to long loose-fitting ones - there’s something about the way they fall around a woman’s curves… Sometimes, less can be more, leaving things to the imagination.
And of course, as @Speakeasy mentioned, the outfit is not so important as the woman wearing it.
/RAMBLING ENDS.
One thing painfully apparent here is the fantasy of being able to judge the book by its cover. Even if we accept that the concern about trouser-wearing women induce lust and that this is as bad as actual sexual immorality is legitimate, making the actual sex life of said women irrelevant: DJS assumes that a woman in a long modest dress would be likely to be a devoted moral Christian, but actually, you can’t tell what she does when that dress is off. For all we know, she could be having an affair, be a regular at the swinger club, be a prostitute that simply doesn’t advertise herself on the streets… Hell, he has no way to know how representative that outfit is of her general dress sense.
Ultimately, the pursuit of forcing “modesty” on women is not only evil, but pointless and futile. As I alluded to, “modesty” is subjective and based on social norms - what DJS may call “modest” may well be considered slutty by those who think a headscarf that fails to the hair completely and ideally, women should not show even their faces in public at all. No matter how strict sexual morality and dress codes are, most women will always be judged harlots by men like DJS, because in reality, the problem is not with the women or their behaviours, but with the misogynists - their utterly messed-up attitudes to women and sexuality, their judgementality, their desire for control and their refusal to accept responsibility for their own sins.