Yeah, I didn't feel like the Tali story was rushed for a few reasons. First, she is part of the original crew and so I felt like I knew her well. Also, she is the first character you come across on your first mission to Freedom's Progress so she is established as a player early in the game. The relationship with Shepard is obviously very meaningful to her that it still felt like a deep connection even if it doesn't take much to get her to fall for you. Kelly establishes that she enters your crew having some feelings for you already. Add all that to the fact that I usually took her with me on missions and I definitely put time into her.