User blog comment:SlasherNL/Liara, Bioware's chioce?/@comment-4835791-20120503095317

Liara is, in my opinion, the most interesting squadmate and is the one who has changed most along the saga (from archaelogist child to lightsided crimelord). While the other characters have a notable evolution she has an appearance in ME2 that blows your mind. I personally think that she also belongs to the most interesting race in ME universe (the most advanced and rich at least). Garrus is great too but it's because of the character itself but while on ME1 garrus isn't much more than a frustrated police officer who evolves into an outlaw Liara has a complete transformation in ME2. Maybe Tali could achieve the same level but they wasted the oportunity making her to appear so late in both games (2 and 3) when her change is also important (Explorer-chief investigator- admiral).

So yes i agree with you that they choosed Liara as the main squadmate in fact she has a role similar to Bastila in KOTOR.