Tali is one of my favorite characters in the Mass Effect universe, and she developed well beyond her "damsel in distress" archetype. When we're first introduced to her we see how much she doubts and questions her own abilities as a leader and even going as far as admitting she feels more comfortable as a follower as opposed to a leadership role.
Her respect and total admiration for Shepard is revealed throughout the course of the series, and more so when it is revealed in recordings found in the game where Tali is making her own leadership decisions by "guessing what Shepard would do if he/she were there."
Her need and potentially developing feelings for Shepard helps Tali grow into a far more confident and interesting character. As her confidence increases she begins to show a good level of humor, sarcasm and a more assertive side in contrast to the shy and reserved character she started out as. Depending on romance options, this new personality was shown in verbal back and forths with Ashley or Miranda during missions. Tali needed Shephard's positive influence to become stronger and more independant.