That's precisely my issue. Sabine's concept feels all over the place, with little to bring it all together or context to frame them with, compared to the other characters revealed so far.
For instance, Kanan is a Jedi who has gone into hiding after losing his way of life. This premise provides context for the rest of his characteristics; i.e. his gruffness, his desire to train Ezra, etc. Likewise, Ezra is a street rat who's always been by himself; hence his loner mentality, reluctance to help others, etc.
By comparison, Sabine's teaser trailer was all about how she's X, Y and Z in isolation of one another without at any point trying to tie them together cohesively or linking one attribute to another. Hence my concern that the creators conceived the character by going "she needs to be X, Y and Z" rather than develop her organically. Basically, my criticism is that the character is either problematic concept-wise or the concept was very poorly delivered in her teaser trailer.
With the others, I can see how the writers probably went about creating the character. With Sabine, I can't. At least, not yet.