It's not a new phenomenon at all. This has been a trend for quite a while now.
However, to justify in-door living, consider this? You spend anywhere from $11,000 to $250,000 for an RV, of any choice. Today's campers are so luxurious, they are just as comfortable and pleasant to be inside as it is outside. In fact, if someone pays a small fortune for an RV, they may want to enjoy the inside of it, more than the outside of it.
We driveway camp (at home) from April to December, and very seldom spend time in the house. Jan, Feb, Mar it's just too cold to reasonabley cost-effectively heat the camper when we have a perfectly good house that needs heat too.
But during the warmer months, we absolutely love hanging out inside the travel trailer, watching television, using our computers, even doing work-from-home (as we both have jobs in IT and can work remotely). We enjoy sleeping in the camper, enjoy the smaller space, compared to the house, and truly love our camper.
We have a fire pit at home, a fire place in the house, we live in the country, it's quiet, we have minimal neighbors, and corn and bean fields for a front and back yard. Dogs run free, no fences, burn our own trash, and can pee in our own front yard (if a car is not passing by). Apart from taking care of the property, or if I'm engaged in a wood craft in the garage, or working my 9-5 job, both my wife and I absolutely love hanging out inside the camper. With our own private campground, it's not really a big deal for us to spend time outside when camping at a State Park. When camping at a park, we are usually out-and-about, site seeing or doing something. When we return, we're inside the camper. We're not hermits, we just find it much easier to relax on the couch than it is to drag out lawn chairs, build a fire, and fight off mosquitoes.
The most important thing is, we enjoy our camper! We enjoy being inside it. It's comfy, cozie, and provides a nice place of solitude for us, calming, relaxing, peaceful, our own little world. We go inside and we are in our own private domaine.
The need to hang out outside the camper sitting around a camp fire is not all that important to us, especially when we keep a fire going in our fire place all winter at home and have a fire pit we use almost every night in the summer, cooking hotdogs, or something on for supper. When camping, it's kind of nice NOT doing those things.
To each his own. This is our world, and maybe one explanation why you don't see us outside the camper all that much at the campground.