I had to address this one as it seems to be lost on most.
When I first saw it I never got the sense that Mako was being relegated to a Damsel-in-Distress. What I got from it was the extremely direct homage to the final scenes in the 1954 version of Gojira. Serizawa’s final moments was, and is, a pivotal moment in Kaiju movie history. The only difference is that Becket lives at the end where Dr. Serizawa fully sacrificed himself to not just kill Godzilla, but take the secrets of the Oxygen Destroyer with him.