(A) suggests not many government are willing to use the strategy described by the author. But whether governments are willing to use the strategy is a separate issue from whether the strategy can be effective. We care about whether the strategy, if used, would work, not whether governments would actually use it.

This tries to minimize the harm to governments from leaving theaters unregulated. It's trying to suggest that governments might not need to worry too much about regulating theater. But whether governments need to or should worry about regulating theater is a separate issue from whether a particular strategy for regulating theater is effective. We care about whether the author's strategy would work to control theater and satisfy the public, not about whether governments need to or should be worried about controlling theater.

This doesn't affect the argument, because we already have a premise establishing that making dramatists honored employees of the government would guarantee those dramatists won't criticize the government. So the fact some dramatists criticize governments that don't treat them harshly wouldn't matter in a world where we're using the author's strategy.

(D) suggests that most theater is apolitical, or at least doesn't show support or criticism for the government. One way to interpret the impact of this is that it suggests theater doesn't present a significant problem for governments. But this point is irrelevant, as described in (B). Whether theater is as big a problem as some governments might fear has no bearing on whether the author's strategy is effective for controlling theater and satisfying the public. We care about whether the author's strategy will work if used, not about whether governments need to or should try to control theater.

This weakens the argument by providing a reason the author's strategy might not satisfy the public's demand for entertainment. Remember, the author's conclusion asserts that making playwrights employees of the government would satisfy the public. But if the public actually dislikes plays written or performed by government employees, that's strong reason to think the author's strategy will fail to achieve that purpose.