Expository, Overheated
R.U.R. has a problem that you get a lot of in science fiction: it has to tell you lots of information about how the world works. And it needs to do that without getting bogged down in boring robotic details.
Čapek's solution is effective, though not especially elegant (somewhat like the clunky robots themselves). First, he includes big blocks of expository text—people will just talk and talk about whatever ideas Čapek wants to get out there. And then, to keep things moving, people will jump into breathless melodramatic cries in order to tell you to be excited. Here's an example:
Helena: Your plans, Harry. When workers rose up against the Robots and destroyed them, and when people gave the Robots weapons to defend themselves and the Robots killed so many people… And when governments began using Robots as soldiers and there were so many wars and everything, remember?
Domin: We predicted that, Helena. You see, this is the transition to a new system.
Helena: The whole world worshipped you—[She stands up.] Oh, Harry! (1.114-116)
Helena starts off by giving a big burst of exposition, telling you that the robots killed lots of people and that that's bad. Then Domin provides a dry reply—it's all part of the plan. And then Helena comes back with an "Oh, Harry!"—big melodramatic ejaculation to grab your attention again in case you glazed over with all the expository burbling.
This isn't to say that all the writing falls into one of these two styles. Čapek can also be witty on occasion, as in the humorous moments discussed over in "Tone." But a lot of the writing style does seem like it's telling you what you need to know and then making sure you're not bored by it. It's as if Čapek is trying to write a melodrama as a political pamphlet, or a political pamphlet as a melodrama.