Discussions around the new user experience tend to be polarized, and I've found that it tends to be because we've got two axes we're trying to optimize around here: Content and Users.
The Content Advocate vs the User Advocate
Not to imply that everyone is an extremist, (although I know some people will identify strongly with one or the other position) but let's look at the extremist viewpoints.
Content advocates believe that the quality of site content is most important. Without quality content, the noise of bad content and broken windows will overwhelm the site, and we'll be left no better than any other random site on the internet. Commonly content advocates will say things like "If they can't read the FAQ and post along those guidelines, we don't want them here anyway. I'd rather have no contribution than something that's potentially negative."
User advocates believe that attracting and retaining new users is important. Without new users, there's no content, right? They also don't want the site to become too elitist by only allowing very knowledgeable or specific users to participate. Commonly user advocates will say "The policy's really muddy, and the question's borderline. It could be salvaged or answered with a comment. Why can't we be nice to this person who is earnestly trying to contribute?"
The arguments tend to flow when these two positions collide.
"User advocates want to coddle the newbies. That's just terrible for content! Burn this junk with prejudice."
"Content advocates might as well just put 'I have to like it' in the FAQ. Their elitism is terrible for users!"
Although these are hyperbole, I've seen many an argument that essentially revolve around these lines.
There's a lot of overlap, but there's also a lot of things that would make the user experience better, but at the cost of enforcing quality content. Both of these are critical to maintaining site health. Neither side is right at the expense of the other. Striking the proper balance is critical.
On Policy and New Users
Policy is an important part of this - policy, enforced consistently, leads to quality content. Disallowing questions and types of questions that seem to consistently produce low quality contributions raises the bar for content, but makes the new user experience worse. The other problem with policy is that the more complex it gets, the more open to interpretation it becomes, and the more inconsistent enforcement becomes. Ironically, the more we attempt to regulate, the more chaos exists.
It's my opinion that simple, sane, enforceable policy that maximizes quality while being reasonably understandable is the best balance here. We've all got our pet peeves about what topics create mediocre questions, and some of these probably deserve to be restricted. However, banning everything we don't like without clearly articulating a reason why they are bad for the site (ie, contrary to the SE model) makes things confusing and difficult for new users.
Reacting to Ignorance
Our reaction towards new users is also something that is important and difficult. Most people on the internet don't read first. Undoubtedly, requiring new users reading the FAQ, read policy threads on meta, and passing a site policy test prior to posting something would improve content, but make the user experience far more difficult.
Hostile reactions to new user ignorance are often encouraged or reinforced. Downvotes, close votes, and hostile comments flow fast and free. In some cases this is justified, and in others we're needlessly antagonizing new users. Being patient, constructive, and understanding can still yield overall quality content without driving potential new users away.
If you're not feeling like dealing with new user ignorance, take a break. There's no need to go off on the 10th person who failed to read the FAQ today - it's still their first time, regardless of how many times we've been down this road already. I actually kind of prefer having a canned comment for new users who don't "get it" yet - it makes it easier to separate my current mental state from the post in front of me, and being able to think it over for a while and get the wording right means I'm more likely to convert someone into a productive user, and less likely to drive them away permanently.
