I think there might be a couple different dividing lines here. #1 is whether you consider "Overlanding" to involve offroad obstacles with lots of technical driving required. #2 is whether you live around your vehicle, or within it.
For me, I don't like "wheelin" and I am not a big fan of "camping" in the traditional sense. I prefer to not be worried about whether I'm going to break something on my rig by trying "conqueor" that next big mudhole or ledge. Also, at least up this way, those that go "wheelin" are typically (I'm probably overgeneralizing here) a little less respectful of the natural surroundings, don't mind lots of noise, and generally don't really go along well with a family-centric experience that I strive for. As a result of all that, I don't need a rig that is locked up front and rear or has 38" mud tires. I do carry winches, but only because with a rig the size of mine, self recovery for any situation is mandatory.
As for living inside vs outside. This is personal preference but one that certainly drives the size of your preferred vehicle. I would consider Boomer to be on the verge of too small with a family of 4. We will eventually be adding a roof tent when the kiddos get a bit bigger (mostly so we can escape them). If we were fine with cooking outside and needing to spend a couple hours setting up camp and tearing it back down again, I think a trailer would be a great solution. That just isn't us. For those that want to live outside their vehicle while at the same time having the "comforts" of a stereotypical expedition-type vehicle, a trailer is probably the best bet due to the issue of GVWR limitations of smaller 4WD vehicles. If you are running trails however, the trailer can be a significant hinderance. I would suggest that most of the rigs on here which are loaded down with drawers, fridges, tents, water supplies, showers, etc etc are either at or have exceeded the manufacturer recommended loadings on their frames and axles. Even with Boomer which is rated at 12500 lbs GVWR, we are within 3000lbs fully loaded of max GVWR. I'm not through with modifications (and may never be), but I suspect that number will shrink by half in the coming years.
I don't think anybody can define the specifications for a "perfect expedition vehicle" as a universal forumla. It makes for interesting conversation, but that is about the extent of its value in my opinion.
"To Each His Own"