You say this, but also she's been paying her bills with just her cleavage since 2010. Obviously teasing and not going anywhere else is good enough for quite a few people.
You have to remember that she's more of a mainstream model that has fans coming from all different circles - cosplay, modeling, video games, animation, etc. She's not just an OnlyFans creator that only has the attention of people looking for something to get horny to. I'm not saying that people don't want to see her naked, but I am saying that the opinions of the casual fan subscriber are probably pretty different than the opinions of guys on boards like this that have been looking through 10 years worth of her pictures.
There's also absolutely a lot of people that are drawn to nonnude models. I never really cared much for Jessica, but there are several more I've followed for YEARS. Some of them ended up going beyond teasing, some didn't. It's difficult to explain the draw to someone else if that's not your thing.
I absolutely respect those that put their content out there, but beyond cosplay I guess? I just don't get it.