I have heard the following criticism of loop quantum gravity:
``Loop quantum gravity is certainly physically wrong, because:
(1) It is not supersymmetric, and (2) it is formulated in four
dimensions''. But experimentally, the world still insists on
looking four-dimensional and not supersymmetric. In my opinion,
people should be careful to not be blinded by their own
speculation and inadvertently mistake interesting hypotheses
(such as supersymmetry and high-dimensions) for established
truths.