Oh my gosh, you've seen it. I bet it's completely enchanting.
That it is. 
I know, you aren't a big fan of large chest sizes in video games, but I didn't think there was anything egregious or oversized about FemShep, or that her bust was being used to sexualize her. She still looked athletic to me.
I don't object to large breasts in video games - or anywhere else. I just get really tired of the focus on T&A in media, and especially tired of the big breasts == sex stereotype (hello, Isabela).
Of course, I'm also really, really tired of having everyone from coworkers and colleagues to teachers, waiters, and other random strangers gawk at my chest.
Also,

that isn't merely form-fitting. It is a detailed sculpture, and Shepard would have needed to have made a mold of her breasts in order to get one made to fit like that - and I have to ask, for what purpose? So she can run around the battlefield all lookee my ta-tas? If it isn't sexualized, then why isn't the male Shep version equally sculpted and molded?
I also suspect that some of us have become so accustomed to the sexualization of women in media that we don't even notice it anymore.