Rooftop tents are the lesser of evils.
It saves the inside of the truck for all your cargo without constantly unpacking & re-packing.
It is a quicker setup and great if you move every day or if you go camp frequently.
If you hit bad weather, it is better than a ground tent. (not as good as inside your truck, but then all the stuff you took out is now wet).
I think most occasional campers can definitely do without. The more you camp, the more useful it is. The less you camp, the cost/bulk factor doesn't add up.
Note- a friend is 6'7" and fits with his wife in the XL Maggiolina, which they really enjoy.
If you are hearty enough to be one of those guys that can lay down on a rock and be comfortable, that's the cheapest and easiest camping of all.
How does a RTT suck?
-weight: any and all add weight in the worst place. But, with sensible driving, won't affect you in any real way.
-bulk: You are driving around with a lot of bulk. Feels like a waste when you are not camping and storing it is a chore big enough not to be worth it.
If you have a tall garage, a winch system would make this a non-issue.
-peeing at night: getting out at night on that ladder sucks.
-Autohome tents:
-the ladder storage is a pain. You can't really store the ladder inside the tent with a lot of bedding and the hooks can dig into and tear the roof lining if you don't turn them down. It will also dirty the bedding b/c the ladder is, well, dirty!
Folded, it's long enough to be a hassle to store inside the truck.
-Maggiolina hand crank is a stupid design. Sure to get misplaced or forgotten on the tent. It also takes like 50 turns to open and close. (I know why the Airtop went with struts instead of that crank!)
-Columbus is easy but flaps around in wind. Fabric is different and doesn't breathe as well as the Maggiolina. If that's going to bother you, don't get it.
-Inside, they are very comfortable. They stay cool in the heat and insulate at night pretty well.
-they keep the truck a lot cooler. Living under the shade of a giant, white box has advantages.
-overall makes camping much easier
-I like that they are aero. The low profile hardshell is great on road and I honestly don't notice it, except in crosswinds where it pushes more than it normally would.
-I can't say it noticably changed my mileage either. I'm sure it's a hit but not significant like a wind blender (roofrack)
-Honestly, for me, the other style of tents were too much setup effort and too thick when folded up.
On a trailer or pickup truck bed, I would prefer the space a ARB or EZ Awn provide. They won't do well in the wind like the Maggiolina, if that is a factor for you.