Verhoeven uses comedic elements to briefly break your suspension of disbelief, so that you're not just accepting the world he's presenting you, but evaluating it as part of a movie. When Robocop goes to commercial breaks, he's not doing that to round out the universe he's built for the movie to take place in, it's to give you time to think about how that universe is unpleasant and avoidable.
Similarly, he doesn't do full-on comedy because fascism is not funny. Certainly you can make a comedy about fascists, but a movie whose main theme is "how does fascism creep into a society" cannot be presented as a farce without losing the sincerity of that question. Just as the remake of Robocop loses its sincere message about the dangers of corporate power in society when you reframe it from the utterly dehumanised person's struggle against a system they physically cannot rebel against to just a guy in a robot suit who magically rewrites his own place in the system through the power of the human spirit alone. It's no longer about the dangers of unelected power, but just libertarian fanfiction about being a kickass cyborg.