I disagree. We know exactly why they work because they are using Finite Element Analysis to test them, just like we would with any other part.

In fact, the neat part about this process is that they are basically using FEA in reverse to create them. So we're using math that we know works from zillions of different validations on traditional parts - and feeding that into an algorithm that just connects the load point dots in the most efficient way possible given certain constraints.

So I would say it's more reliable than you give it credit for.

But the biggest downside, and the reason you won't probably ever see this style of design used more widely is that manufacturability is a huge pain and/or expensive. Outside of 3D printing technology, these things are very hard to actually construct.