The Pope's decision not to give Henry an annulment was political as was Henry's decision to split from Rome.
I was Anglican for almost 30 years; my decision to leave was not based on political events of 500 years ago.
I would agree, if Henry had not applied for a dispensation to marry Catherine, which was granted.
Because of the dispensation, the request for an annulment was rather more than a usual annulment.
Catherine had been engaged to Henry's brother, which was why a dispensation was needed.
Full Disclosure: I got a dispensation to marry my first wife who was also my first cousin. That may be part of the reason why I am now of no religion.