Mariner's original post laid out heterogeneity as a criterion that the WEC has got it right. However, isn't it also true that designs converge over time as the engineers inch closer to the optimal interpretation? As Fat Boy said, cars "will only be as fast as [they're] legislated to be". Failing that, you end up with BoP.
Why? What do they know about LMP technology that all those dunces at Audi, Porsche, Toyota (and even Peugeot) don't? What's their track record? Nissan are not one of the great motor racing names are they?
Why do people see something different and novel and immediately assume that it is must right and that all the current accepted technological answers are wrong?
It's not about right or wrong, it's about better or worse given a very specific regulatory landscape.
LMP designs have converged around a relatively consistent aerodynamic and powertrain concept; the variation so far has been in how the manufacturers are ordering off the powertrain menu (engine size and type, hybrid implementation). I think it's fair to say that this concept is the "best" one from a basic, minimally regulated point of view.
What I think happens though is that the rules converge around convergent designs, too — they become focused on reigning in the development down certain avenues, so you get things like shadow plate rules for faired in wheel pods and so forth, regulations around wheel sizes, weight distributions, etc. that manage the detailed implementation of a given general concept.
I see the Nissan effort as capitalizing on a blind spot in the rule book — the ACO has been so focused on mid engine RWD layouts and the attending aero concepts that it has left a gap that can be exploited in a totally different way.
Thinking that Nissan may be on to something doesn't mean you think Audi, Porsche, Toyota, and Peugeot are dunces, it just means you think there's a possibility that the rule book has left a gap — a funny shaped, front-engined gap — that is worth exploring, but was not obvious because you can't see it from the "best" starting point.
Whatever you think of the DeltaWing, this is a team of experienced engineers with access to state of the art simulation and analysis tools. It might not work — even well-funded, relatively conventional designs can fail. But I think it's unfair to say it can't work because it's different, or it can't work because it's Nissan.