Honestly, the :Vulcan Hello" itself was a major point of the episode in that I don't see it as Burnham doing what she did because she didn't like her Captain's decision; again the situation was similar t Spock's in that she honestly and deeply felt (another thing she's coming to grips with in rediscovering her Humanity and emotion) that if they didn't do what the Vulcans did when encountering Klingons (fire first) - EVERYONE on the ship would die, and the ship would be destroyed.
^^^
In her mind the Mutiny she was undertaking was the ONLY way to get everyone (her Captain and her Crew and ship - which she felt was her family) out of this situation alive. Could she have been right? (IE Had she successfully fired first would the situation that ended up happening where her mother figure and Captain and many of the crew ere killed not have occurred?)
We'll never know (and I suspect not); but again, she didn't simply decide to Mutiny because she disagreed with the Captain, she did it because she felt it was the ONLY WAY to save her 'family'. <--- For me that is VERY 'Star Trek'.
Also, given her testimony to the Board of Inquiry at the end of the second episode - yes, she began to fully realize that that action was very wrong and started to understand what it cost her and it's something I'm sure we'll see her character realize more as the series progresses. <--- And that's yet another thing that's very "Star Trek': A story about the Human condition.
So yeah, I can honestly see why you don't think this is 'Star Trek' so far, but I want to explain why I do.