As one of the people being characterized as having an 'itchy trigger finger' on the delete link, I wanted to offer up a constructive suggestion for how to radically reduce the number of deletions while still accomplishing the goals that the deletions have been trying to meet. I don't necessarily believe that this is exactly the right recipe, but I hope that there's a contagious germ of a good idea in here.
As a convention, delete almost nothing. Maybe leave all deletion to diamonds. The question of spam/offense flags I leave to others' opinions.
A strong merge tool and a redirect mechanism. This would be viewed as distinct from deletion. This process would move the valid answers to the chosen target question, remove the answers from the closed question, and link the closed question to the chosen target to get to the answers. So we retain the full search goodness of the closed question. Link the other way as well, in case some of the moved answers are hard to understand without the context of the closed question. Instead of a vote to move a question from closed to the merge process, diamonds and other with some amount of rep (> 10K?) would be trusted to do this as individuals after some time has passed in which the question has not reopened.
Closed questions for S&A, NARQ, and OT would be indexed differently. The search field would search the ANSWERS, but not the QUESTIONS. So any answer goodness remains reachable, but troll, poll, and dull questions would appear rarely on anyone's screens.
No new votes on closed questions and their answers.
No rep from closed questions and their answers. I could see that this could be a headache for the devs. Perhaps a rule like: votes are wiped from a closed question once it's stayed closed for two weeks? Yes, this would unfairly penalize people who put effort into answering poor questions. I ask: how often would this punish the innocent? Perhaps infrequently enough to be tolerable?
In other words, my proposal here is to make closing somewhat more stringent -- to move much of the purpose of 'delete' into the orbit of 'close,' reducing the desire or incentive or need to delete. Once a question is closed, it's off the front page and is no longer a gross 'broken window.' If we then remove the rep value of inappropriate questions, and we make them less prominent in search, perhaps that's all.
Or, if you don't like this (and someone doesn't), I have another idea. Radical Edit Surgery. Faced, for example, with a troll question that has a useful answer attached, edit it down to a sensible question that goes with the answer.
** ANOTHER EDIT **
A really gnarly problem here is that answers are permanently nailed to questions. We don't have votes to delete truly awful answers to good questions, and we want to preserve good answers to bad questions. But we don't want to live with the bad questions.