This is a much more meaningful, thoughtful post than some of the others.
I will agree with you that two caring parents, one male and one female, is from everything I've seen and read the best way to raise children. It raises the most well adjusted kids with the least psychological problems and most successful long term outcomes.
Where I would differ is marriage. Whether you have both signed paperwork and had a ceremony in no way impacts the development of the child. What matters is: what attitudes does the man show to the child, the woman to the child, and what interactions do the man and woman model in front of the child in how they treat each other. Having your name in a legal roster does not change these interactions. Nor, in truth, does non-monagomy...unless of course you're bringing all kinds of women to the house....which is not good for a kid, but you shouldn't be doing that anyway.
I believe strongly in a committed relationship, i.e. one in which the two partners share a deep romantic and emotional bond for raising kids. It does not seem to preclude sex with other individuals on a FWBs basis on the side for sexual satisfaction, and certainly does not require marriage.
Now we get into the respect word. Your statement to me, implies that you feel it is in some manner disrespectful for a man and a woman to consensually agree to allow the other to sleep with other people. To me, it's the opposite. That seems to show deep respect and trust.
If you feel that is disrespectful, I would ask you why you feel that way? My guess is that the answer you come up with will not be based on anything hard, but rather some feeling. Perhaps a moral imperative, perhaps a "feeling", perhaps a sense of wrongness, etc. Any of things suggest something you have been trained to believe. It may or may not be true. Challenge those beliefs, and see if they hold up.
There is an association here, but I don't think there is evidence to show it's causal by any means. It could just be that those that wait are those that are the most committed to marriage as a lasting endevour. It's the mindset, and not the waiting, that has everything to do it. I'm not contending that's the case, but it's one possibility. Without some solid multivariate analysis there is no way to just know the answer.
I would argue the trends don't show a casual link. In more recent studies, they have found that women with 10+ partners prior to marriage have the highest divorce rates. Probably not suprising, as it seems reasonable that a women that sleeps with many has: a high sex drive, likes variety, is used to those, probably not big on heavy commitment, etc. Not suprising she would bail when things get rocky.
Oddly though, it's women who had two partners prior to marriage that had the next highest divorce rates.
Women with 3-9 partners were much closer to those with zero or one partner prior to marriage than to the other cohorts.
This is a good question. My question then is, does it produce results? In a small percentage of cases the answer is a clear yes.
In most the answer is: we never find out.
In the majority of the remaining minority, I think the answer is not really. I'm sure you get some satisfaction from being a "good person" and "fighting the good fight" and such, but if you're in a fairly typical marriage with sub 1x/wk starfish sex, lots of nagging from the woman, relatively high incidence of drama, and many "rules" for what you can and can't do...I would ask...are you really happy?
I'll use parents as an example. Except in rare cases, the majority of people love their parents quite deeply. On a regular basis, we have all heard about situations with parents where we know the relationship is a strain for either the child, parents, or both. The classic overbearing, dominant father perhaps comes to mind. The kid may love his father deeply, but at the same time his father is a source of frustration and unhappiness; and he will receive recommendations from his friends that perhaps he should cut this guy from his life. You love him, you can work hard to make your interactions with him better, but at some point it's just not going to happen. You then cut him out of your life, and while it saddens you to do so, as a person you become much happier with that drama sink and negative energy removed.
We readily do this with parents or friends, but are slow to do so with loves, especially married ones. I don't think it's noble to stick out a marriage where you are treated poorly, of if many things that do not make you happy are demanded of you. Making an effort to be a good husband with a positive attitude, who listens well and tries to support his wife is a wonderful thing. If you put in a good effort there, and drama, verbal assaults, withholdance of sex, and large numbers of rules and expectations are still received, it's time to bail in my opinion. Your putting "making the marriage work" ahead of your own happiness. That doesn't make sense to me.
Maybe it would if you had kids. But if you had kids with someone with those kind of problems, you either are terrible at screening women, or made a BIG mistake on choosing to have kids with someone that was already giving you drama and rules.
My main point of contestion though is just don't get married in the first place, it's not necessary to be legally married. You can be everything that entails without the risk of a legal marriage. If you absolutely must...get a pre nup. A strong one legally. And realistically, and I'll stand by it, don't commit to monogamy. The problem is people change over time. Significantly in some cases. Statistically, she is going to start shutting off sex, losing interest, giving more drama, etc. It's biological. Non monogamy drastically reduces the severity of most of these problems.