You're right and all but... While it isn't *emphasized* in Metroid... Samus sorta does the same. "Space Pirates" are a race of sentient creatures she mows down without any remorse. Four times, the last on their actual homeworld (Corruption).
That's all fairly justifiable though, she's mostly just clearing dangerous bandits as part of a mercenary contract (and assisting in a pre-existing intergalactic war in the homeworld case). In the first two cases it's Zebes, the world where she were raised and where the pirates slaughtered her adoptive parents.
Not Adam FLIPPING Malkovich, but the Chozo.
But in Metroid 2 she kinda slaughters an entire race of beings (metroids) down to the penultimate one. Then takes the sole survivor and sells it to scientists for energy research. Samus was a stone cold, even vicious, badass.
(Other M says "Oh wait she was obsessed with being a mother to that baby [she sold] and would hesitate for like 15 seconds when facing a metroid [she exterminated the race of] and is short and the Prime series didn't happen" aaaargh)
It should also be noted that Samus' fuckhughness is also essentially a plot point, as while it is not stated even the most casual look at things suggests the genetic modifications she received from the Chozo as a child are responsible. In everything that considers it other than Other M, Samus is freakishly, inhumanly fast and strong. That's before the Phazon corruption, the X-parasite, and the Metroid DNA to nullify the X-parasite.
I guess the official word is still that Other M is canon and the excellent Prime series isn't... But I still hold hope that they'll softly reverse that. Sweep Other M under the rug. It was almost universally panned, after all. If Sakamoto hadn't designed the earlier Metroids as well, it would be as forgotten as Hunters.
As I told you a year ago the last time we collectively hated on Other M, that idea is mistranslated. Nothing has been booted out of canon, what Sakamoto said was that he didn't consider the Prime series while making Other M, something which is rather obvious from the end product.
On the other hand, the next Metroid game isn't even going to be about Samus, so...series in limbo, really.
The events of Prime would have come before Other M, and clash too much... Counting Prime, she would have faced Ridley 7 times before Other M. Which makes her breakdown even more absurd. She also specifically says that it's the first time she's worked with the Galactic Federation since leaving Adam, which is a specific "Fuck off" to Metroid Prime 3. He wasn't "unaware" of Prime, he was just a jealous hack with an unfortunately large platform.