How do you judge whether Descent of Man is a text that can change the public position, or too radical and not worth defending? If you only defend things that don't get a negative reaction, and anything contrary to the current dogma gets a negative reaction, you'll likely never get anywhere.

Also, the strength of the reaction against a non-conformist text is not really strongly correlated with the degree to which it's non-conformist. Dogmatics police small deviations precisely because they don't want an incremental strategy to work.

I'm sorry, I know that I'm reading a dead discussion. But your comment shows that you have no idea what impact The Descent of Man had. Both good and bad.

You can argue for or against it on many grounds, ranging from Darwin's sexism to the importance of treating humans as just another animal to its misuse by the eugenics movement culminating in the Nazi excesses.

But arguing against it because it did not impact the public position shows an ignorance of history.