I've got a few thoughts on this too, although I'm not a moderator so the answers you've gotten from L.Dutch and HDE may be more what you're looking for.
The challenge here is in error rates - because nobody cares if questions that should be closed are closed, or if questions that are good remain open. The problem arises when questions that should be kept open are incorrectly closed and when questions that should be closed are incorrectly kept open. Nobody is perfect, so we all make mistakes in different degrees.
What I notice happening recently is a massive decrease in incorrect non-closures, with a corresponding (small) increase in incorrect closures. This has been mostly driven by one of our new moderators, L.Dutch. He's certainly not afraid to use his mod-hammer to close questions! This is a new perspective for the site, as mods in the past have been pretty reluctant to use their overriding powers. In the past day, at least five questions that I could find have been closed by L.Dutch before they reached the five-person normal review. Some of these were clearly in need of rapid handling (e.g. here, here, and here), while others were more debatable (e.g. here and here). In the first case, those questions deserved to be closed rapidly and decisively, and we all are indebted to L.Dutch for his swift action. In the second case, these are less-obviously in need of mod-hammering and more in need of responsive and constructive comments. It appears that far fewer questions were mod-closed in the past - the last time this came up, someone complained because four questions had been mod-hammered closed in five days. That's much less activity than we've seen recently.
The mod hammer is a fickle tool because it overrides the normal review process in which a consensus is reached in order to close a question. This drives the mods much more into the spotlight and makes them far more visible, especially to new users. As I mentioned earlier, this has driven down our incorrect non-closures and the site is a lot "cleaner". However, there are also questions falling under the incorrect closures, and we're throwing some babies out with the bathwater.
This would be a trade I'm willing to make, except that we've already got an awesome team of active reviewers who aren't mods. We close questions all the time as a community, which allows the mods to work behind the scenes and step in in a more friendly first-contact to new users. The easier it is to mod-hammer a question closed, the more likely the community will also close it quickly.
My final point is that mods can also hammer questions open immediately, and that's a tragically underused tool and one that could engender a lot of goodwill towards our mods. Although I'm unable to easily see the stats on mod reopenings, they feel highly unusual, and that's just a shame. Our mods have, in a way, the best sense of what fits on the site, and as soon as they see something fixed the instinct should be to get it open immediately. The community is also much worse at reopening questions, so this is the perfect place for our mods to pick up a bit of the stack - er, slack.
I have a few specific requests to make, from this. First, please direct new users to our Sandbox!! It's a great place for discussion, style, and scope questions, and is perfect for new users. (Incidentally, everyone is welcome to give feedback there, and I think mod perspectives would be especially welcome for new users.) Often, the question needs a bit of touching up and can be ready for Main with just a few comments and recommendations.
Second, L.Dutch, please cool it with the mod-hammer closings. Trust your community to decide which questions are in need of closing, and leave it to the democratic (oligarchic?) process that's already in place. I remember you being a highly active reviewer when you weren't a mod, and it feels like those voting habits haven't changed, despite your voice being much, much louder now. Remember that the more obviously a question needs to be closed, the more likely it is that the community will handle it quickly and judiciously. Consider using your close-votes now as the fifth or fourth or even third vote, not the first and only. I firmly support HDE's stance here and in other places, as does the community, and will quote from the mod bible to back this point up:
The ideal moderator does as little as possible. But those little actions may be powerful and highly concentrated. Judiciously limiting your use of moderator powers to selectively prune and guide the community — now that’s the true art of moderation.
Finally, to all mods - don't be afraid to mod-hammer questions open! Being told by someone with authority that something has been fixed is a delightful feeling, and I personally believe we can afford the small increase in incorrect non-closure rate. Although I can't seem to find it, I remember a post (I think by Monica) about this site being rapid-close rapid-reopen, but we're forgetting to reopen.
Massive respect to L.Dutch: I just noticed he reopened this question as soon as the problems were fixed. Thanks for being such a responsive and active moderator!