I've thought some more about concrete reasons why I think the outfit simply looks 'professional' and isn't necessarily intended to be overtly sexual.
The neckline, it doesn't go down far enough to be revealing of anything. It barely exposes any more than the exposed face everyone else has. Beyond that she's completely covered up. Hopefully if she's in an exposed environment she can close that up, of course.
The boob rack, well, it's a form fitting space outfit. Is that inherently sexualizing? Does it need to be flat and unremarkable like Anderson's suit to avoid being sexualizing? The female heavy armors in ME1 had pronounced "boob slots" as well, were those bad? I see it as attractive, sure, but not, you know, OMG HOT. More on that later.
The skirt could just as well be an extension of her shirt. There was art earlier in the thread that put Kaidan into a similar torso+skirt outfit, and I know that art was done in jest, but still, it didn't strike me as particularly sexual, nor does the concept on the whole, male or female. What is inherently sexual about it? They have skirts on the men and women in Dragon Age as well, and sometimes in DAO in combat you could see the woman hunched over in such a way that the opening of the skirt was right there in your face, but is that designed to evoke "Man, that was hot"? It just struck me as a kind of comical situation to find myself in, looking up the skirt of some angry woman with weapons in both hands.
The boots and high tech stockings just go with the rest of the outfit. I doubt it would work as well with combat boots. Form over function, yes, I'll get to that momentarily, but on the matter of it being sexualizing, the only way I see this being sexualizing is inasmuch as any formal suit with an emphasis on form is designed to be 'attractive.' But there's a difference between being designed to be attractive and being designed to be sexualizing. There's a difference between a business suit that happens to be hot, and a stripper outfit. Everyone would like to be attractive, but sexualizing brings an element of exploitativeness into it. I feel pretty sure, in this case, that the look they're going for the former, 'attractive.'
Beyond that, like I said, she's (almost) completely covered up and she's got a few token hard armor pieces, and by my admittedly low standards regarding practicality in armor, I'm fine accepting that as a suit of light armor. Does light armor fit Ashley's character? It could. It depends on what her character is in ME3. We don't know yet. Now, does the fact that she chose a suit that emphasizes form over function fit Ashley's character?
I suppose it does not.
But I still don't see it as particularly sexualizing.
As far as her having an alternate "combat outfit" that is actual heavy armor, I'm all for that. Though, if this is an alternate outfit here, it seems unlikely that it won't be a combat outfit itself...