It is for many, but not all. Generally speaking, it&#x27;s less of an issue for interpretations that give an epistemic role to the wavefunction.<p>Perhaps an extreme example, but in the &quot;QBist&quot; interpretation the wavefunction and Born rule are merely a convenient calculus for the prediction of future interactions with the system. It&#x27;s not the only way to encode this probabilistic information, but it&#x27;s nice and compact. The issue is then  not &quot;why the Born rule?&quot; but &quot;why this particular set of probabilities over potential outcomes?&quot;.<p>Then again, a lot of people find the very idea of epistemic interpretations of quantum theory distasteful, especially in light of the Bell, Kochen-Specker and PBR type inequalities.