Stupidest idea in a decade or two.
Lol, I wouldn't go that far. I think ground tents with good mattresses are better suited for most people. Investing in an Exed Megamat and a decent ground tent will have similar size and comfort to most RTTs, and it will weigh less.
I've done extensive research on RTTs and used multiple styles. The kind that flip open have some benefits over ground tents. You can leave sleeping gear inside (mattress and bedding), the setup time
can be faster than a similar sized ground tent (I'm thinking 8-person Coleman or something like that), you are off the ground (if that matters to you), and if you can level out your rig then you're guaranteed a level sleeping spot. My first tent was a flip open kind, and I wouldn't buy another. Generally they are much heavier than a ground tent, take as much or more time to set up for the size tent I actually need, and getting them on and off the vehicle (plus storing) can be a hassle.
A hard shell has more benefits over a ground tent. Opening is generally faster, because they are assisted by gas struts or electronics. You can leave sleeping gear inside. You have a hard roof over your head, which can help with noise or extreme conditions. Some of these can be built lighter and low profile, which helps with vehicle dynamics (although a ground tent and good sleeping pad still wins in the weight category). Some can also be used as roof racks.
I started building a wedge style, hard shell RTT. I made the frame, base, and top out of wood. I still need to sew the fabric walls for it. It takes about 30 seconds to set up, and I'm guessing will take 90 seconds to close when I get fabric on it. If I decide this one works well enough, I might make one out of aluminum and composites. There is a good DIY RTT comunity on Facebook, and most people have less invested in building one than a quality ground tent.
Is an RTT the be-all end-all in camping? No. Do they have some benefits over a ground tent? Yes. Is it worth it? That's up to you. They are becoming a fancy "fashion" accessory within the overlanding crowd, but there's no harm in that.
If you want to look at some cool stuff, check out the following:
1)
GoFast Camper
2)
RipCord's DIY Wedge Camper
3)
RoofNest (Sparrow is my favorite out of their offerings)
4)
FreeSpirit (Odyssey is my favorite out of their offerings)
5)
Smittybilt (the budget option)
The old tent:
The new tent: