Essential.
I suppose you could argue it's not essential to survival... either is money, freedom, or your left arm, but you probably don't want to be without any of those things either. And the 50% who don't consider it essential, I doubt you'd give up sex unless it was because you were brainwashed by a religion or some temperance movement.
We're literally built for sex physically and psychologically. It's the main driver of our evolution. And if not having sex, then your significant other is really nothing more than a house/room mate.
I have a few arguments:
First, it helps a lot with mental balance →which leads to good sleep which leads to all sorts of other life benefits, like mental acuity, and getting stuff done. Without it, say goodbye to good nights sleep and productivity.
Second, as previously stated, your relationship might as well be a living arrangements → Sex brings people closer together, and more willing to share. It's a borderless realm between two intimate people (minus certain bodily functions... in most cases, I've heard of something called the Cleveland Steamer they presumably do in Ohio, USA).
Third, physical health → there is exercise and there is thatttt kind of exercise. Sex is to a really great workout as cocaine is to cannabis... except unlike cocaine sex is one of the healthiest things you can do. For those who haven't done cocaine, think of weed, but add the benefits of coffee along with the chill euphoria and none of the haze that cannabis adds, then throw on 10 layers of unearned confidence. To paraphrase Rick James: Cocaine is a hell of a drug, and good sex is a hell of a workout.
Physiological health is a big part of it too, if your significant other has a UTI or something and you can't have sex for a while, you'll notice that anxiety starts to build, anger at things that don't really matter. I can guarantee you that nearly all those voraciously angry social media people (who are always offended, cynical, always attacking, people that seem to skulk platforms 27 hours a day) are having little to no sex, and would calm down if they were getting it. We had a saying back in the day when people were just pissed off at everything all the time, "you need to get laid", and there is a lot of truth to that.
Four, the reset button → This kind of ties into the first point I made, but I want to go a little more in depth... In other words, there is always something to look forward to. Even if you're married, busy 23 and a half hours a day and all you can afford are a few quickies; and most of that half-hour are showers... it's like hitting the reset button on a chugging Windows 98 computer. That's why, IMO sex is essential to marriage and the chaos of life balance between work and raising children (especially if you move around and don't really have a reliable support base). Like, when you see people with kids breaking up in divorce, the same story seems to be the most common one: poor sex life... "needing escape/space" is typically just code for poor sex life; being a good dad 3 days of the week...
Five, the motivation to live up to some potentials you didn't know you had → while I know culture has changed a bit because of temperance movement brainwashing, generally speaking, if not in any committed relationships, then the motivation to find sexual partners is an ever present thing. It motivates people to drastically improve themselves in ways they weren't otherwise considering. Work harder for money, work harder for fitness, and spend more time on the aesthetics of looking fucking great. It's a great motivator for getting clothes you wouldn't otherwise consider buying, or going out to social events more regularly. When single, or dating casually, generally speaking you open up your networking way way more than when you're settled down (in those cases, I find if anything, your social networks generally shrink/become tighter in the middle and looser/smaller along the periphery).
For the record, I don't believe in using sex as a bargaining chip for doing more house work and such, and anything like that is pure bullshit.
On the topic of temperance movements, I don't at all buy into the idea that no orgasms gives you special powers... if anything, it's quite the opposite. Temperance movements also try to push the narrative that pounding off is immoral, unhealthy, or can even ruin your sex life.., nope! Sometimes you have to get to work early, and you need to pop one off before going. It's just a part of our lifestyle. Having breakfast isn't going to destroy your dinner/supper. Fuck fasting, intermittent or otherwise :)
I describe myself as a little dose of toxic masculinity.
