Don't have time to look through all of your examples, but I took a look at the first one. It's an open-ended question that doesn't have a single, definitive answer. It will generate discussion forever. That's the reason that it was closed (emphasis mine):
> As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit...polling, or extended discussion.
Joel Spolsky and Jeff Atwood have a very strict and specific philosophy/opinion regarding what kind of questions and answers make for a "good" Questions & Answers site. There are numerous blog and Meta StackOverflow posts talking about this philosophy. The idea behind suppressing extended discussion is that it makes it harder to find practical answers to actual, real-world problems when they're buried underneath a sea of un-focused discussion.
EDIT:
I think the generalization of community moderators on StackOverflow as "self-important" isn't entirely correct, nor am I convinced that it's even relevant either. Are there self-important people moderating StackOverflow? Probably, but that doesn't address the fact that people are following strict guidelines for usage of the site that were agreed upon over time by the site's founders, together with the most active participants of the site (or at least, those who most actively chose to participate in Meta).
These guidelines were put in place to "make the site better", at least in the opinion of the founders and the aforementioned participants of Meta. They weren't made up so that a bunch of "self-important" people could feel "self-important".