Good point.
> The Mideast is nuts for other reasons, which has caused them to go overboard.
Including being out in the hot desert sun too long...
> Their violent obession with extreme female modesty must spring from a sense of insecurity from most young men's poor economic prospects, and from the physical decrepitude of old men wealthy enough for a harem.
You've undoubtedly hit that nail on the head. Now, your mention of harems brings up another sidelight, which I don't claim to have an answer for, but perhaps you have some insights.
As I have heard it, in some cases, the eunuchs who guarded the harems were castrated (testicles removed) but were otherwise intact, meaning that they could perform intercourse, and presumably (since they still had prostates) could climax. But no offspring, guaranteed. (In some harems all genitalia were removed; I'm not speaking of those here.)
There was a tacit allowance whereby the eunuchs could fool around with the wives, since doing so couldn't produce false heirs to confuse the family lineage. This was allegedly viewed by the ruler of the harem as a mixed blessing -- on the one hand, other guys were boffing his wives; on the other hand, the wives were happier and entertained (important, if one has, say, 100 wives), and after all, the ruler owned the eunuchs and could have them killed if they got too out of line.
I haven't gone looking for citations on that story, but if true, it suggests that chastity was less prized than knowledge of paternity. Or it could be the story isn't true...
Although the majority of societies have accepted polygamy, that does not mean having an unlimited number of wives is a good thing.
I suspect societies that support some men wealthy enough to afford vast harems staffed by eunuchs, are societies that have exceeded the natural balance of power among their members, resulting in great poverty at one end and excess riches at the other end.
Either extreme is likely to produce aberrant behavior—so one should not take the behavior practiced by the desperately poor or the idle rich as representative of normal human behavior.