1. Is there NA that's really all about the sex? Yes, I'm sure there is. Just like there's some adult romance that's all about sex. Does that mean ALL NA is just about sex? No.
2. YA can be hot too. I've read some YA that was a bit more descriptive. And there's also adult romance that goes into no detail sexually. I don't think adult, YA or NA are defined just by sex or a lack of.
3. Is there anything wrong with the NA books that ARE mostly about the sex? No. If that's what an author wants to write then they should GO FOR IT. It's their right and for anyone who likes to read it, GO FOR IT. There is nothing wrong with a little sexiness ;)
Excuse me if this post ends up being all over the place, and a warning now that it will be long, but here are my thoughts.
What makes NA, NA, you might ask? Why is it different than YA or Adult? It's not just sexy YA, it's not just characters in college. I think it has to do with a few things. Age is part of it, content is part of it, HOW the characters deal with the situation in the book is part of it.
Let's look at adult romance first. When I think of adult I think of characters who are more set in their life. They're not "new" adults. They're settled into a career, or having issues because "at their age they SHOULD be more set in a career". They either have kids or they're to the age where everyone is wondering, "why don't you have kids at your age?". They've been divorced or other characters in the book are wondering, "why haven't you been married at your age?". They aren't adjusting to being on their own for the first time in their lives. Aren't usually living alone for the first time. They're a little more "seasoned" at the whole, being-an-adult-thing. Usually they're looking for something different in their lives or they're in a different place than a NA character may be. I've talked to people who only read adult and have no interest in NA because they don't want characters who are still partying in college or who don't know how to live on their own or who have no idea where their life is going or who still make "silly" juvenile mistakes. Again, in adult novels, they're not "new" at the adult thing. (remember this is just MY personal opinion)
Now let's look at YA. Most YA there's still the comfort of having your parents, or an aunt or an uncle or the state if something goes wrong. Forgive my reference to CHARADE, but I look at Colt. He's losing his mom. If this was a YA he wouldn't really be alone once she died. Even if he had no other family, the state would step in. There would be more options, more people to help him. Most YA characters are still, to a degree, "being taken care of", or have the option to be. They may be preparing to become a "new" adult, but they aren't there yet. Their parents can still be held accountable for them. There are "perks" to being a minor. To a degree, I think the stakes CAN, not always, but can be higher in a New Adult. And when I say that, I'm not talking like Hunger Games or something like that. Yes, that was YA with some of the highest stakes there are. They had to kill each other. By typically, and more so in realistic fiction, the stakes can be higher in a NA. New adults are going to be held more accountable than a YA character. Consequences are different. And again, there's still the safety net of being a minor. There's a lot of power in that.
Content. Yes being NA gives typically, not always, but typically gives more freedom for content because usually the experiences are different. A lot easier to experience with sex when you don't live with your parents. A lot easier to get into trouble or make mistakes or whatever, whatever. I look at myself. I had the comfort of home, living with my mom. No job in high school. I was responsible, but my only responsibility was school. I was lucky and that was comforting. Then I graduated. Within a couple months of my graduation my mom had moved to a new state, I lived alone for the first time and had my first job. I was dealing with MUCH different things than I had been just a few months before. I remember not long after my little five hundred dollar car broke down. I had no money to fix it. No mom there to help or at least you know, give me a ride to work. No work, no money, no money no car. It was my first time dealing with those things on my own.
Sex seems to come up a lot when discussing NA though. I'm going to refer to Charade again for a minute. Did Colt and Chey have sex? Yep, they did (but I think it's important to reiterate that some of my YA characters have sex too. In real life, I struggled with confusion about sex a lot as a YA and NA and I like to show those struggles in my books). Back to Colt, he's also dealing with losing is mom in the book. Cheyenne has some major things going on in her life too so no, the sex wasn't the most important thing in the book. Charade was about life, death, pain, growth, love, friendship, family, honesty, and getting over the past (as are a lot of other NA books). Was it hotter than my YA? Yes, it was. Was it hotter than all those adult books I've written that sit on my computer or were out in the past under super secret pen names? LOL. No, it wasn't NEARLY as hot as what I've read or written in adult books. Which again, IMO isn't really important. I don't think how hot the sex is should be such a major talking point when it comes to NA. It shouldn't be what defines NA, but I feel like I have to bring it up because it's the number one thing I hear about when people discuss NA.
I have zero idea if I have made any sense with this post, but yeah, these are my thoughts on what makes NA, YA and adult books. It's stakes, content, experiences, where the character is in their life, age and probably many more things. BUT I think because of the reasons I wrote above, because of what YA readers are looking for in their YA and what adult readers are looking for in their adult, New Adult needs it's own category.