It's easy to say that Captain Phasma was hyped up only to fizzle in the movie. After all the person with even less screen time is Poe (j/k). And yes she doesn't seem to have much to do when she is on screen, and maybe there are some cut scenes that would elaborate on her role. But...
I wonder about why she basically let herself be used to get captured and turn off the shields when she should have totally resisted and tried to escape or warn someone, knowing that if she died in the attempt that at least the intruders would be stopped. Well, what if she was actually sympathetic in some way to stopping StarKiller Base from being used again. Maybe Finn's defection actually affected her somehow, made her think about what the FO was doing and if it was the right path.
Or maybe she was distracted with female problems (I know, that's sexist, but someone was gonna say it!)
Any other deep thoughts on Super Tall Shiny Stormy?