Yea, nice. But the thing is, if you could make a large, low mass vehicle, you'd be able to make existing designs lighter as well, lessening the load on the heat shield.
It's more than that. The shuttle had an L/D of 1 to 1 at 40° AOA. It had too much lift - hence the S turns. Yet they went for that approach anyway.
The point is that you
can build a low density high strength design; perhaps as importantly, you probably couldn't have in the 1970s, especially when, with the exception of the U-2, most research for high speed high altitude vehicles had been on things shaped like HL-10s and X-15s.
Like everything else in engineering, it's a design compromise. The shuttle's TPS does present some challenges, but on the other hand it doesn't take a week to reenter, it's relatively easy to launch, and can carry heavy payloads to and from orbit.
A reentry vehicle like this presents some colossal challenges, less so from an engineering standpoint, and more so in required paradigm shift. To suggest that this is a "better" alternative than low aspect ratio, blunt vehicles, categorically, is absurd, I know that.
I think it can be done and I think it would be interesting to see someone do it, but I don't exactly have a list of wherefores and whys here either.
I think, "low density" is a better term than low wing loading or high L/D in this context.