In this article, http://thinkingtorah.blogspot.com/2012/01/modesty-and-women-problem.html, Rabbi Israel basically argues that: 1) the halachic restrictions on contact between the genders is sufficient and no additional restrictions are necessary; 2) that the Charedi tendency to add additional restrictions results from their seeing women solely as sex objects, and thus necessitating a complete removal of women from the public sphere; and 3) that halacha does not restrict the mixing of the genders. I agree fully with Rabbi Israel on the first point, and I partially with him on the second and third points, but with some qualification.
First, it is inaccurate to say that halacha does not restrict the mixing of genders, as there are certain situations where it is prohibited. Of course there's the obvious restriction of separating men and women for davening. But it's also explicit in the gemarah and Rambam that during yom tov celebrations the genders were separated. This separation was due to the joy of the occasion, which might cause frivolity, which might lead to inappropriate contact with the opposite gender. In addition, Rav Moshe Feinstein writes in Igros Moshe that it is absolutely assur for Jewish day schools to be coed starting in middle school. He also recommends separating genders even from first grade, so that kids of the opposite gender will not retain their relationships once they become teens. When coed youth groups were started, teshuvos were written by the Sridei Aish and Tzitz Eliezer to justify the practice, ostensibly because social interaction among teens was generally considered inappropriate.
However, nowhere is there mention of separating genders on buses, in the workplace, or in any other public sphere, where the concern is simply not wanting to see or be in close proximity with a woman. That is where Charedim take it too far.
Rabbi Israel also suggests that it is a Charedi thing for men to look at women only from a sexual perspective. I think that Charedim are not much different than the rest of Western society in this respect. The difference is that the rest of Western society has no problem with viewing women this way, and those that do have a problem with it don’t care enough to try to fix it. The Charedim see it as a problem, but take extreme measures to remedy it. Instead I suggest, and I think Rabbi Israel concurs, that halacha contains the correct balance between permissiveness and restriction.
Now as far as Rabbi Israel's contention that the halachos restricting the mixing of genders are sufficient, I fully agree with him on this point. Looking at Shulchan Aruch Even Ha'ezer Siman 21, you will find that if you follow the restrictions listed, you will be more than adequately protected from any possible aveirah.
The question is in situations where halacha is not absolutely clear, for example when it comes to seating at weddings. I have mixed feelings about separate seating at weddings. While I happen to find it very annoying when I have to attend a separate seating wedding when our only connection to the chosson and kalla is on my wife's side, I also understand why you would want separate seating. Firstly, if men are seated on the women's side, they will likely watch the women dance. Secondly, the potential frivolty associated with a wedding seems to resemble that of a yom tov celebration and might warrant separate seating for that reason as well. Of course the real reason some people make their weddings separate is just to show everyone how frum they are, even though they themselves find separate seating annoying. I had separate seating at my wedding just to show how frum I was, and now that I am married I realize how annoying separate seating is.
Luckily, I have grown out of that stage in my life, but I have also discovered something else that Charedim in Israel might try following: keep all of halacha, no more and no less, bein adam leMakom and bein adam lechavero, master all of that, and then start thinking about taking on chumras.