While those postulates are described in words, they are based on strict mathematical formalism. Terms such as "hermitian", etc. are solidly grounded in it. So to me, these postulates are nothing more than a bunch of mathematical statements.
I think this is unlike SR, which truly states a "physical" situation. While you can translate SR's postulates into mathematical operations, I believe Einstein made them starting with physical intuition, which is why they are easier to comprehend. The QM postulates, on the other hand, makes no sense if one doesn't understand the mathematics, which ties in to my other assertion on why QM is so difficult to understand for most people.