Maybe this is going to anger you, but Samus's personality in Other M matched up surprisingly accurately with who I imagined beforehand. Though I agree that her portrayal could use some serious improvements.
which metroid games had you played beforehand? regardless of your answer to this however, fusion is the only other metroid where she has much dialogue, she wasn't a silent protagonist before but...there was a lot of room for interpretation. particularly if you've followed the series for 15 or 20 years as many people have, you're much more malleable 3 years in.
obviously my Samus is going to get into a PTSD when she sees someone who she thought was dead for good, killed her parents, and came close to relieving her of her own life on the prior encounter, among other things such as prompting the main events of Super Metroid in the first place.
ridley has come back from the dead before and she never freaked out that way. and yes there is a degree of realism for a woman to freak out when a big ugly monster that killed her parents appears, but she was never a wholly realistic character prior to this and, fantasy isn't supposed to be bound by the shackles of reality to begin with. some characters are likeable because they are larger than life heroes that likely couldn't exist in the real world, samus fit into this mold pretty nicely in previous incarnations, a realistic woman isn't infiltrating a hostile planet of aliens and eradicating all of them alone. even if you agree with the characterization, it's still goes against the series' minimalistic tradition which has never put an emphasis on samus' relationships before, with the exception of fusion which also had mixed reception.