2 things. 1- I love your style, the quality of the concept art and the colors, I adore most of the work in your gallery and love your concepts. Now on to 2 where I will ramble- I don't understand how this could be efficient in any sense of the word, the purpose of this design seems to be objectify women in the name of sci-fi/fantasy. No one bats an eye at this, or questions its practicality, but if I were to draw a mech with a glass bubble over a mans penis everyone would ask my motives, think I am a pervert etc etc... Ramble over.
Now I shall ramble. This is a typical double standard, yes.Though, I do not want to judge the artist based on it for that exact reason. It is art, and he is quite a brilliant artist at that. Now, look at the difference of the situations you described. If this was showing only the female genitalia rather than her chest, there might be quite a few that would "bat an eye" as they would with a male. But, if in the same situation, you drew a mechs with a males chest exposed. Well... Point being, the only reason anyone would ever say anything about a females exposed breasts is because for ages it has been instilled in us that this is "wrong". But what is wrong about it? It is portrayed as arousing? Would it still be "arousing" if for the past 400-500 years women were to go shirtless as often as males? Food for thought.