This thread represents a very blinkered view of 'suitability' in a royal bride. It has come down to a critique, in hindsight, of why Alexandra's personality made her unsuitable for the position of Tsarina. In my view the reason why she was unsuitable was not because of her personality, but because she was extremely unlucky.
Two major factors determined why Alexandra did not appear to be suitable, and they are evident only in hindsight. Firstly she did not produce a male heir early in her marriage. It took ten years of her time as Tsarina, giving birth to four girls in succession before Alexei was born. Secondly when she did have a boy, the child was unlucky enough to inherit her haemophilia gene, and that was only a 50-50 chance. Those two factors put an enormous emotional strain on the Tsarina, as they would have done to any royal bride.
Just think what her life would have been like if her first-born child had been Alexei, born healthy. In all aspects except his illness he was a son to be proud of, so she would have had the chance to become the darling of Russian society, and with no need to produce a child every two years until she had born a boy. She would probably have had two more children (allowing for 'the heir and the spare' and perhaps one other) and they might have been Olga and Tatiana, but the pressure to produce a boy would have been removed, and she would have had no need to rely on Rasputin for more than casual religious guidance. No problem.
Actually there was a third reason why she was unlucky, which was to follow in the footsteps of her socially outgoing,extremely popular and comparatively young mother-in-law. If Maria Feodorovna had been other than what she was, Alexandra would have had a much easier time of it in Russian society.