Or at least Nintendo made it fit theirs. Somehow, we welcomed it with open arms regardless of how "Metroidy" it was.
The thing is, Prime and Echoes had a lot of sequence-break-friendly glitches, much like Super did. Sequence breaks and openness are two of the biggest factors in how much I enjoy a Metroid title, whether the openness is intentional or not. I'd wager that anyone who spent hours as a child breaking Super Metroid every which way feels the same.