I don't understand why Stack Overflow Inc the company chose to hide away the reasoning behind this change, but a Stack Overflow moderator (Cody Gray) has shared a partial account of it over on Meta Stack Overflow. Here are some snippets:
This decision was made with the benefit of hindsight: Jeff's solution [halving rep for question upvotes from 10 to 5] seemed logical enough at the time, but after nearly 10 years of it being the standing policy, there is now enough data that we can look back and judge whether it was really having its intended effect. Sara unfortunately doesn't go into very much detail about this data-led re-evaluation in her blog post, presumably because it is intended for a more general audience than the folks who read Meta.
The fact is that the changes made back in 2010 simply weren't having the intended effect of improving question quality. Reducing the amount of reputation gained from upvotes on questions did little or nothing to address the problem of users earning reputation from low-quality questions. Worse, it merely served to make it that much harder for users who were asking useful, high-quality questions to earn privileges.
Data tells us plainly that voting skews heavily towards answers. Even if the net reputation gains are made equal (as they will now be), folks who write good answers will still be earning reputation faster and more easily than folks who write good questions.
It then goes to talk about how the company has sought to improve question quality in other ways:
...Recently, increased effort has been targeted specifically on addressing the issue of declining question quality, including some of the things that Sara calls out in her blog post: a wizard to guide users through the process of asking questions, improved post notices that do a better job of communicating why a question was closed, and better moderator tooling behind the scenes to deal with less-than-stellar contributions.
The logic presented there actually sounds quite reasonable.
According to a comment from a staff member who wasn't in the core team behind this change but was indirectly involved, there was also some work done involving surveys and focus groups, though it looks like none of the results of that will ever be shared:
I wasn't heavily involved in that project, but this was FAR from a unilateral decision executed haphazardly. What I could see was weeks (maybe months?) of discussion and outreach with satisfaction surveys, focus groups, and an extensive discussion with the Moderator representatives of your communities about if/how to roll this out. Maybe it was felt we couldn't crowdsource this decision and discuss improvements with thousands or millions of users every time; I don't know. Meta SE hasn't exactly been a constructive place to bring anything lately (which is understandable, but still...) – Robert Cartaino ♦
If this reasoning had actually been shared with us, and opened for any sort of discussion, I think my only concern would have been whether increasing the rep reward for question upvotes might lead to a decrease in upvotes on questions as upvoters raise their standards; leading to a worse experience for conscientious new users as even more reasonable-quality questions get no response whatsoever. That's a question that can be answered with data in a trial period.
I think the response to a post like this would have been cautiously positive:
Reducing question upvotes to +5 rep didn't improve quality: we intend to reverse it and boost quality smarter
Nine years on, halving the rep for question upvotes from 10 to 5 clearly hasn't reduced bad questions. Tools like the SO question wizard and improving question closing have been much more effective. We're planning on continuing the "pearls not sand" principle by focussing on those tools, and rewarding quality questions by restoring them to +10 per vote.
Here's the data behind this [link]. Before we go ahead with this change, is there anything we didn't think of?
I don't understand why this has been presented the way it has been: cooked up in secret, presented as if it's a rejection of the idea of question quality mattering that is being imposed unilaterally, when a good case for it could have been made that I think many users would have agreed with.
It feels like the leadership at Stack Overflow inc are now deliberately going out of their way to present things in a way which will anger and alienate their users. Why?