They added heels to an already sexualized character. Zero Suit Samus has been sexualized from the day she was shown. I don't see how having heels is really that big of a deal considering she has always been either half naked or in a catsuit that shows off her butt and chest. Heels realy don't change much, considering she's still in the catsuit, her chest and butt are still shown off, it's the same as always just with different footwear. Metro is fans never complained in the old games when she'd pop-up as a half naked pixelated woman, but now that she's in heels DEAR LORD THATS SEXIST. I'm just confused by the people saying that it's a disgrace to the fans of the series event though it's been this way for a long long time.
I understand that you're confused, let me explain.
There have been aspects of the characterization of Samus that've been criticized. We go through a 10+ hour adventure filled with emotion, sweat and tears and poorly-made written-down maps, and in the end, gets greeted by the woman who's behind the robot suit we experienced our adventure with, surprising and enriching us with the fact that a woman did all this by herself. That mental image of Samus has stayed with gamers for many years, including me. It wasn't like she randomly popped up without any clothes, that only happened if you actually knew it would happen or if you beat the game fast and grabbing many hidden items, otherwise, she would probably stand there without her helmet saluting you or something. It was a more well-contained secret, that didn't alter the characters overall image. However, those elements ARE problematic and are also criticized, and have been long before the Smash 4 heels were revealed. I took a course back in 09 and spoke with female gamers that expressed the positive aspects of a mostly unsexualized heroine that connected to the player through her actions, rather than her appearance, but also expressed dissapointment over the fanservice (for men) that stood as a reminder that the games are marketed to males.
The outrage and criticism towards the heels comes from the reaction to the overall direction Nintendo is going with the character and the Metroid series as a whole. With Other M, the critics and fans showed that they want Nintendo to take a new direction with Samus character and the Metroid series. I for example, don't want Nintendo to continue this way with the Metroid series, we already have oversexualized female action stars that caters to the male (heterosexual) crowd. The heels did trigger the feelings the fans had after Other M, and that may be why people who haven't taken all these aspects I brought up into consideration see this outrage as overblown. But the problems are not just the fans like me. It's that we live in an age were many people deny that sexualization, psychological impact, commercial impact and medial influence exist. Instead of having a more constructive debate where we ask "what should Nintendo do" the debates are instead all about semantics with irrelevant questions and arguments like "but shouldn't women be allowed to be beautiful" or "no, sexualization can't mean anything except for this specific meaning I made up in my mind and can't link any sources to".
Years of research have proven that sexualization in media does in fact exist and have been widely discussed long before the 90s, 80s, 2000s or New 10s. Also, please consider that gaming is going through a phase now that other mediums like art, literature, film and tv entered a long time ago. We have to accept that games have gone mainstream and like any serious media is going to be taken seriously, criticized seriously and analyzed seriously.
I have to excuse myself for any grammatical errors on my part, but I hope that this explains it?
Also note that this is my interpretation of this.