For me, the draw to a RTT is ease of setting up/striking camp. I've done just about every style of camping you can imagine: tent, backpacking, canoe, bike touring, survival, meadow crashing, etc.
My favorite style of camping was my VW bus because I just pull into camp, jump in the back and do whatever I want to do. When it's time for bed, I just pull out the bed and I'm there. I can even take camp with me when I want. I want my 4Runner to be able to handle similar duties, and that means it needs to be able to setup and take down easily. It doesn't have the same level of design that the bus did, so I have to do it myself. Further, I anticipate a few additions to the family before I get rid of my 4Runner (and my next bus will likely be a passenger model), so the interior will be even more taxed (the interior of a 4Runner is MUCH smaller than the interior of a bus despite the bus being so much smaller on the outside... The Tar sis (forum doesn't like the first 4 letters...) was inspired by a bus, I just know it!).
The attraction to a RTT with a 4Runner is that it's easy to just flip the tent open (versus fiddling with tent poles and tarps and such), camp, and then fold it back up and move elsewhere. This still leaves you with the entire interior to use for tools, parts, cooking gear, personal storage, etc. If you opt for the sleeping platform route, you loose a LOT of storage space AND you loose the ability to sleep more than 2. Since my target is long term accommodation for 4 (expedition rig remember), a RTT is about the only option to maintain mobility even without interior storage for stuff.... It may not make sense with what's on the market, but you'll have to live with that for now. My design is still pending.