The problem with your premise is that all of Freud's stuff isn't considered total bullshit. The mass media, science magazines, and materialists like to present it that way, but psychoanalytic and psychodynamic traditions (depth psychology) are still alive and well. It is, perhaps, not quite as prominent in experimental psychology (which I'm guessing is what you're talking about), but it's certainly still a force in clinical work. Humanistic, positive psychology, cognitive-behavioral, gestalt, and most other approaches were inspired by, informed by, and still use parts of depth psychology in their approaches.

I think you're mixing up clinical psychology and experimental psychology. The aims for both will vary, and I tend to agree with you that presenting psychology as a hard science is ludicrous (but unfortunately the only way to get funding). You're also right about the political component of psychology (your homosexuality anecdote); psychology can be used as an instrument by the leaders of society for political, social, and economic gains and control. That doesn't mean it has no contribution to man's knowledge of the world.

Just because the newer approaches appear to reject older theories does not mean the older theories aren't useful. Newtonian mechanics explains phenomena quite well for everyday living. Relativity was a revolution in the field but there's a still a place for Newtonian physics (i.e. you don't have to erase the classical theory). The way knowledge evolves in these long-standing fields isn't as mechanical as I think you're claiming it to be. Science is much more complex than that.