In this Gamespot article, they discuss the inspiration that drove Phantom Liberty;
As previously revealed, Idris Elba will be playing Solomon Reed, a master spy turned sleeper agent, newly awoken to assist V on their mission. Reed is very loyal to his employers, but is also principled and caring. In the course of the expansion, he'll make choices, and V will have a chance to affect the outcome.
Songbird is another NUSA agent and the third-most-important in the expansion. Sarzyński described Songbird as a parallel character to V; each of them are reflections of the different lives the other could have lived. Apparently, she was a divisive character in playtests, with some players sympathizing deeply with her and others totally rejecting her.
Also in a related article they justify the price of $30 for the expansion by saying;
"As a director, we are involved in that we just recommend to our board what we think that amount of content is [and] what is the value for the player and the actual value in the game. And that’s the extent of it."