Critics of my screen play tell me that I have done a good job of developing the story, less so in developing the characters. A couple examples follow:

The main character is a woman who is the "fifth" partner in an advertising firm, for which there are only four corner offices, none of which is hers. The woman is incensed with this fact, especially after the managing partner hints that she is better than his other three partners (all four of these are men). 

The woman's main subordinate is a "pot-shaped" man who nevertheless makes it to CEO because her guidance set him on an unlikely trajectory. (Even after she leaves the firm, she "guides" him by "proxy.") He never expects to make it to the very top, which would be a daunting task for any advertising executive, never mind a pot shaped one. 

Others tell me that it's not enough to assume that the reasons for this woman's discomfort or the man's lack of confidence are self-evident, but go into their backgrounds to explain why they feel this way.

Do most authors and critics feel that this is true? If so, what are ways to develop the characters of these two people over and above the storyline?