It’s important to keep in mind that, as has often been said, we writers are not the audience, we are the product. The audience is the advertisers and the Machine Learning bots.
It’s also important to note that customer satisfaction does not factor in to Quora’s metrics about changes. As is made clear in this discussion of how Credentials were rolled out:
A whole bunch of users deleted their bios in disgust; but the remaining bios met Quora’s idea of what counted for a good credential better. Argal, Step 3: Profit! The annoyance of those users is immaterial.
What Quora think we’re gaining has been outlined in the announcement: Changes to further emphasize canonical questions by Sumi Kim on Quora Product Updates. Rather than cite the announcement, I’m going to cite Nancy Jacobsen’s summary of the rationales, with her refutations.
Although I seriously doubt that this change will actually accomplish your stated goals, I certainly hope you broadcast this post to all users—not just followers of this blog—because we’re about to be inundated with hundreds of questions about this change and we users have to carry the brunt of user support.
Prevents answers that appear irrelevant if the writer didn’t read the question details. — This most often happens because the interface doesn’t show the question details, for instance in Requests. And, if you answer a request in-line rather than in the question window, you never know that there were details. So, this problem is not a result of details per se, but of interface issues.
Prevents answers that respond specifically to the question details but appear irrelevant to the main question.—This is true, but if the details were adequately displayed (see above), this wouldn’t happen. It also happens because questions get posted before the OP can add details.
Increases the likelihood that answers to a question will receive upvotes because those answers are more widely relevant.—Doubt it.
Makes it easier to search and find your question.—Doubt it. This is more a function of the Search feature.
Makes it easier to know if a question already exists and to decide whether to ask a new question.—Probably not. The related questions are already displayed when asking a question and people don’t look at them anyway.
Decreases the likelihood of duplicate questions.—No, see above.
Prevents questions from becoming overly detailed and personalized, and thus less canonical.—And at the same time, less useful for the person actually asking.
Makes it clearer whether it makes sense to merge questions.—Doubt it. As it is questions that appear to make sense to merge are constantly being unmerged, details or not.