We have a 26-fit TT, and yeah, we're mostly only inside at night or when it's raining. However, we go to Highland Games, holding a booth for our Scottish clan, and sometimes we invite people over for a wee dram, so it's good to have a place to "entertain." When we dry camp with friends, we trade dinner nights with them, so again, nice to be able to cook properly and have space for everyone to sit. We have a dog, and he doesn't enjoy sitting by the fire as much as we do, so a TT with room for his crate was essential.
But ours is not a huge RV, and we wouldn't want one because we'd have to have a TOAD, and it wouldn't be big enough for our Scottish booth gear - can't take the big rig onto the field for set-up - or to pile friends in to take day trips while dry camping. Anything bigger than what we have would length us out of some of our favorite campgrounds, too.
But different people enjoy their time on the road in different ways. We too wonder why people want to go out in a lovely woods and then sit inside and watch TV while the rest of us can't hear the forest for their generator, but ....