Disagree. The crying was a poignant moment that was striking because of how unusual it was. It added to the scene and to the character.Being a fan doesn't make you better at something. It makes you more knowledgeable about the source material with can also work against you if you come into it with preconceived notions. And considering she cried at Spock's funeral, being a fan did nothing in that scene.
Additionally, remember that Alley was not playing a Vulcan. She was playing a half-Vulcan/half-Romulan who was supposed to have hints of emotion showing through.