Well, I disagree on two fundamentals. For one, I think MShep's armor was equally sculpted. I think there's just more to notice with Femshep by virtue of breasts arguably being more noticeable.
Do you
honestly not see a difference between, say this:

and this... ?

... because the top image is more along the lines of the fit for female Shepard.
Also I don't think she would quite have to get a mold of her breasts, she would just need measurements and precise cup size so that the armor could be tailored for her--and I can think of a few very practical reasons to do so (Namely, comfort and better mobility).

Do you not see the effects of gravity here? That armor presents a breast sculpture, with every arc and curve rendered in loving detail. It would look no different if she used spray paint on them. Since breasts actually come in not only different sizes, but also different shapes, densities (amounts of sag), positions on the chest, etc., there's no way you could get it to fit like that with only measurements and cup size.
And, btw - I feel that comfort and mobility would be better served with a comfy, supportive bra and some room for movement - not some rigid material encasing them individually.
I don't necessarily disagree that part of the reason is to make the appearance aesthetically pleasing, but that's just it. I don't oppose a design predicated on whether it's aesthetically pleasing.
You do, I assume, agree that that people have different tastes wrt what is aesthetically pleasing.
At the risk of sounding trite, the female form is very pretty, so utilizing does a lot of the work for a costume. I don't think we can fairly accuse every example of accentuating a female figure of being sexualization, because I think sexualization takes more than that. Sexualization/objectification in fiction involves diminishing a character, breaking them down into sexual parts. There are times when I saw that occur in the trilogy, but never with Shepard.
Objectification is reducing a character (or person) to an object used for sex.
As defined in the
wikipedia, "Sexualization (or sexualisation) is to make something sexual in character or quality, or to become aware of sexuality, especially in relation to men and women." Alternatively,
wisegeek says "Sexualization is the process by which a person, group of people, or object comes to be seen or interpreted as sexual in nature."
An armor like the following is form-fitting and accentuates the female form without presenting a detailed sculpture of the breasts: