If you let the viewer in on the secret of what's going on with the two Lazurus before the characters figure it out then you make the heroes look stupid. The idea is for the viewer to follow the heroes trying figure out what's going on. It's a revelation for the viewer as well as the characters.
Yeah, the science is wonky, but the point is to deliver a tangible sense of drama and jeopardy rather than a hard science dessertation.
Re: "Plato's Stepchildren." Yeah, the antics were embarrassing and humiliating to the heroes because that's the whole point of the scene,
to show how degenerate the Platonians are. Hell, today people openly humiliate themselves on television without any apparent regard for how asinine they look. They seem to have no genuine self-awareness or even self-respect. And because it's in the real world they're publicly humiliating themselves far more than what we see in this TOS episode. TOS' heroes were bullied by immoral degenerates rather than willingly denigrating themselves.