Good question. Yes, Shaw's theater of ideas would deal with exposing fickle social boundaries, but ideally for Shaw, his works would go deeper than that. In addition, they tackle more than one idea, more than one issue, at a time. In Pygmalion, this meant looking at social prejudice, sexual bias, how brutally the society was divided into classes, how resistant society was to science and change, and—and this is what makes it especially insightful—how all of these interact. The prejudices support the division into social classes; the resistance to science makes the class structure seem nature, and so on.