Blocky icons aren't masculine. You can't show me a man shaped like that.A circle is more 'feminine'-looking than a hexagon because of its inherent, smooth shape
No freaking comment. I just want to highlight that.
It's not really that odd of a concept. Curves are associated with women while angular shapes are associated with men. Artists working on modern games are aware of this fact and make an effort to remove some of that solid, angular plate armor on their female models in order to show more curves.
And yet it reads to you as masculine. Why? If you can give me a reason that doesn't boil down to "green is a boy color because it's not a girl color", I'll be surprised.
Green, or to be more specific the green CRT look reminds me of nerdy men in their garage building computers. It's not just a color, but an entire style associated with a male-dominated industry; especially so when thinking of the time that kind of color scheme was in use.
It should be incredibly harder to defend, because it's part of the system by which cultural biases are propagated and marginalization occurs.
It's a tendency that may never be completely defeated, but we shouldn't hesitate to poke it with a stick every once in a while, question it in ourselves and others, and definitely not defend.
Male default (along with white default and other defaults in the dominant cultural paradigm) are part of what makes it hard to get representation for people outside the default in "mainstream" entertainment media.
For instance: a movie or comic with predominantly or exclusively white cast is "for everyone"; there's no special point seen in its casting, but something with a minority cast is seen as "special interest" with a narrow appeal. It's a self-fulfilling prophesy because as long as the people producing and distributing the media position things according to the default, the audience becomes more accustomed to seeing things that way.
See also: A Batman/Superman comic arc called (and about) "Supergirl" was retitled as "Apocalypse" when animated, because a movie called "Supergirl" would have been "for girls." Disney's adaptation of Rapunzel was retitled "Tangled" so that boys wouldn't see it as a "princess" (girl's) movie.
Content producers operating inside of reality must bow to this paradigm to some degree, but that doesn't mean anyone should be defending it... and ideally, every once in a while, a content producer will do something to challenge it or make people think about it.
This stuff matters! This stuff is the reason that DC Comics feels comfortable saying that 25% of its editorial staff being women is a lot, or why some people think that 3 out of 9 supreme court justices being women represents some alarming trend of women taking over. Nobody blinked when man after man was appointed, but two women in a row is seen as an agenda... men are natural happenstance; woman are a special case.
Related reading:
http://perilousadventures.net/0809/nonexistence.html
http://booklifenow.com/2010/03/ nisi-shawl-and-cynthia-ward-on-roaars-and-the-unmarked-state/
http://thesocietypages.org/socimages/2010/11/21/ gendered-toy-advertising/
http://thesocietypages.org/socimages/2010/06/11/ a-cop-car-for-you-little-police-boy/
http://thesocietypages.org/socimages/2010/01/09/ socialization-and-gendered-job-segregation/
http://thesocietypages.org/socimages/2011/08/02/ kids-luggage-normalizes-gendered-occupations/
(That last one is especially egregious: boy's version of carryon luggage is blue and marketed as being for little "pilots" while girl's is positioned as being for "pilot assistants", which isn't even a real thing... the co-pilot is also in fact a pilot. Somebody realized that calling the girl's version for being "flight attendants" was "not politically correct" but it never occurred to them to just have them both be pilots? Or to sell one kind of luggage? Or market the colors independently of gender/perceived appropriate future careers?)