Zero interior space.
An outrageously high lift over height.
Can you carry enough fuel to get out of town.
It would be easier to service or repair a 1960 Unimog.
Nor exactly maneuverable.
Did I mention zero interior space ?
The only Hummer with any credibility for family excursions would be an H3.
But yes, an H1 driver would be great fireside company. They are cool if not practical campers.
I get you're trying to make a point but most of what you wrote is hyperbole at best or completely wrong.
There is plenty of space for overlanding/camping/expedition. As much as many other choices. Much more than a two door Wrangler for example.
Lift over height - yes it's outrageously high. (But you also get 16 inches of ground clearance - stock.)
Fuel - 42 gallons (51 in Alphas) gives you ~400 miles of range. 500+ in an Alpha. (10mpg is bad, but not uncommon in a lot of overlanding vehicles.)
Service or repair - You can get them serviced at any GM service center. It's just a plain Jane Detroit diesel - nothing practicality difficult about working on a Hummer compared to many other options.
Maneuverable? - They are large - just like a lot of other full size trucks. Nothing particularly bad for what they are. But, yes, they won't turn like a short wheelbased Jeep or Jimny.
H1s are different from other options but not nearly as bad as you think. They're just more industrial and utilitarian (like old Defenders). Many other options are more creature comfort filled and have more civilized (or should I say civilian-ized) qualities but H1s can go everywhere all the other ones can go... and yes... they are just a little bit cooler if not as practical.