Silla Guarda 'Inside-Out' collection  

Function vs. clever
The chairs above are certainly clever-ish, but as many have pointed out, have some functionality questions.
SDR's spoons, on the other hand, perform their duty well. The fact that their design incorporates a cleverness doesn't detract from their function (or won't once the correct material is used).
I don't think most of us object to cleverness. It is only when that cleverness overwhelms the form and practicality of an object do we object.

Given
two chairs of the same seat-and-back heights and angles, the one with any amount of curvature to those surfaces, no matter how sleight, will be more comfortable than the one with flat surfaces. For all their expense, these nesting chairs will not be perceived as comfortable for any extended seating. The leg issue mentioned above compounds the error.
I can attest to the comfort of the 40-4 stacking chair, a paragon of functional minimalism.