I don't know if people made the point already or not, but here's my take on it.
>> Samus Aran has always been sexualized in every game she's been.
Counter Point: I guess they sexualized Ellen Ripley in Alien, but they were brief moments that incorporated into the story--a moment of near ultimate weakness when the creature reappeared upon the shuttle. But rather than keep focusing on her body, her eyes were the primary movement, showing her determination to persevere against an unknown--and hostile--lifeform at her lowest. I don't particularly think the games previous to Zero Mission and Brawl were going out of their way to oversexualize Samus--it was just a bit of a reward for completing the game so quickly. That's it--just a reward. You shouldn't have to feel pressured into completing the game that fast for anything other than just seeing her in a more relaxed outfit--she earned some R&R after some of those missions!
That being said, Samus' original character inspiration, Ellen Ripley, was supposed to be a female character in an often masculine role, having to kill Aliens (and the queen!) in order to continue her life. The most memorable moments of those movies were when she blew an Alien out of the airlock, confronting the Alien Queen in the lair, driving the APC to save the Marines, Fighting the Queen with the Power Loader--none of these memorable moments were particularly sexualized, and Samus Aran was much the same--her most memorable moments were fighting against some of the foulest scum and villainy in the galaxy, trapped underground against parasitic life forms, or squaring off against her own mirrored antagonist. None of these situations were sexualized to any degree--the only sexualized portion of her was at the end of the games.
Compare this to games such as Zero Mission and Other M. In the former, we spend a good chunk of the last 10% of the game in this undergarment state--a sexualized role to be certain, but one could look past that as you bravely navigate through the Zebesian Ship. We could get past that. Other M, on the other hand, it seemed like there was no pressing plot point to her being in the Zero Suit other than to just give people a look at her incredibly oversexualized body--a body we now have to look at all the time in Smash Bros. Games. It isn't an extreme detriment to the character, but it is one that lessens the impact of her overall personality. Hanging out on her ship after a long mission in the Zero Suit or some other form of lingerie is acceptable--its not outside the realm of reason. But some of the scenes she is in with the Zero Suit (not to mention the fighting exclusively in it in the upcoming Smash Bros. game) seem forced and out of character for her--especially the overall trainwreck of the Other M game as a whole.
So no, while sexualization of Samus Aran isn't particularly new, it is more often/visible/illogical at this point. The new look of Samus' Zero Suit looks odd (what's the difference between this and just a padded, black bodysuit with connection nodes?) especially the roller-derby heels. Seriously, they look like something out of an 80s rollerskate arena. So her high heels have jets in them--I can't imagine something that compact and small being that useful. Most women I know also hate high heels because they hurt for long durations of time. So... That's my two-cents. Hope it makes sense.