In the early NES Nintendo games, most every game could be beaten in a matter of hours, and a fair amount of them in under an hour. The good games of that era rewarded you with a more difficult version of the game, or alternate characters to play the game through again. You got to play this version of Samus if you beat the game super quick.
I tried real hard to find video of the game without her wearing the armor in the original Metroid aside from the source sprites I referenced to make this, but turned up with nothing on YouTube. Also, I am aware that this isn’t referred to “Zero Suit” until later in the series, but I am taking some liberties here, folks. =)