Like what? Maybe Tali, but all of the others have a far greater aptitude in combat.
She apparently doesn't know where any of the Cerberus assets are, and the last thing ME3 needed was more helping out characters and their daddy issues. We had enough of that in ME2.
It doesn't even make sense for her character to be there. It would make much better sense to run across her as she targets Cerberus operations.
I don't know about combat aptitude. Miranda is a biotic which in terms of the lore make her much more useful than the squadmates who can just shoot a gun (which Miranda can also do very well). She also has tech knowledge.
Also, in ME3 Tali and Garrus are both dealing with father issues, Ashley has to deal with family issues, Liara has all sorts of issues, Javik is the last of his species, EDI has romance issues, Cortez is... point is Shepard is still dealing with people's issues, Miranda would fit right in.
As for Cerberus assets the game just kind of breezes over quite a bit of that, which makes it more an issue with the main plot than Miranda.