i think martha’s story was the perfect one to have after rose left.
people were going to hate her regardless. the audience was predisposed to dislike martha regardless of her storyline. if this had just been ignored, and just had martha and the Doctor suddenly become the best of friends, this would have just given people a reason to call her a mary sue, and she’d be ‘replacing’ Rose, and the Doctor would be an asshole for getting over her so quickly.
The unrequited love story bypasses all this, and the culmination of the finale is incredibly empowering because she removes herself from this unhealthy relationship. The series is told from her perspective. Although it would be great if you are capable being able sympathise with both Martha and Ten, you are shown her thoughts and feelings, you’re not supposed to think ‘wow rtd wants me to hate martha because ten said she was a novice gee whizz’. We are constantly shown things from her POV, we’re shown her reactions when she hears ten talking about rose. It’s not like RTD intended for Martha to be unsympathetic, she’s the companion, and you’re supposed to like her, hence the constant ‘Very good point. Brilliant, in fact’ ‘No, but I like that. Good thinking.’ ‘Martha Jones you’re a star’, ‘Oh. Oh, Martha Jones, I like you!’, from Ten.
If you have been rooting for Martha, that moment when she gets out at the end of S3 is excellent pay-off and you’re supposed to cheer for her. If you’ve been siding with ten the entire time/still grieving Rose, that scene is a wake up call as you’re explicitly told, Martha Jones is NOT second best, she is not replacing Rose and never was. she’s her own person, she is good and you’re wrong if you missed that. and you should feel just as chastised and guilty as Ten does when she leaves.
people often say that RTD companions all had identical arcs of ‘lacks confidence and has low self esteem »> is shown she’s special by the doctor’, but i think that’s a really lazy and textually incorrect reading
Rose is incredibly confident, she just lacks direction in life and the Doctor is a catalyst for finding that better life.
Martha is brilliant and not unconfident at all, she’s just too selfless and devotes far too much time trying to help others (initially being the peacekeeper for her family, and then acting as emotional support for Ten), and she learns by the end of the series that it’s ok to be selfish and think about your own well being sometimes
Donna is the only one who you can accurately say starts off as unconfident and lacking self belief, and all it takes is someone to believe in her for her to become extraordinary (not necessarily the doctor, as shown in Turn Left).