Those who currently hold the majority don't want any ranked choice that might undermine their position. Worse, since there are only two parties, the other side is very often seen as deranged, corrupt, and evil, that should be kept away from power with any means short of a nuclear strike.

Only when there is a sizable number of disgruntled voters who are unhappy with both the red and the blue, and would vote for specific decent people, not party affiliation, then RCV has a fir chance of being adopted, I assume.