I understand that programming questions asked here are supposed to be constrained and answerable and should not result in a more open-ended discussion. However, I do have sometimes have programming questions that are more conceptual and opinionated. What's a good, well-moderated site that would allow these kinds of discussions? I'm wondering if there's something as well executed as the Stack Exchange network but for highly subjective questions.
The objective answer to your question (which I, quite subjectively, don't like), based on what usually happens, is "No". People in programers.stackexchange.com will downvote and close open ended questions. Also, the requisite of that questions can be answered means in practice that the answer is not known perhaps to the one asking the question, but it is known to a significant proportion of people in the programmers.stackexchange.com, so it "can" be answered. A good and objective question with no known answer and particularly with multiple answers will be downvoted and/or closed; again, this is an objective account, I don't suppose that is expected to work that way.
What's a good, well-moderated site that would allow these kinds of discussions?
Computer Programming topic: https://www.quora.com/pinned/Computer-Programming
Search "programming" topics: https://www.quora.com/search?q=programming&type=topic
Stack site (shutdown)
defunct Stack Exchange site Not Programming Related
Why did it fail?
In 2010, a Stack Exchange site called Not Programming Related came out of Area51, the Stack Exchange staging zone. NPR was supposed to be a site where questions that were too subjective / broad for Stack Overflow would find a new home.
[...] Turns out that while everyone loves those questions, very few are actually willing to spend any time to answer them (seriously), and maintain and moderate them. [...]
Personally, I can understand that when you allow opinion based questions you allow any answer to be correct which may encourage new non-programming users, or lower the knowledge threshold that is expected for users. This may cause these less experienced users to creep into other forums and lower the quality of Stack sites.
However, I don't think shutting down that site should have been the answer. Subjectively and naively, as I wasn't around for the site and don't know about issues it faced, I would think that eventually those issues would be dealt with by voting, editing existing answers, or wiki answers.
I agree with Jeff's comment:
It's strange. To me, a programmers life revolves around open ended thoughts. I know all of the code that I write is open ended. I can always find a way to go back and make it better, or think of an entirely new way to reach my objective.