This discussion, spread as it is over three? four? threads, is developing a bit of a whack-a-mole character. Nonetheless:
There appears to be a universal consensus that we need to stop deleting questions as duplications when we haven't made arrangements to preserve good answers. Someone is still regularly nominating dups for deletion. Several of us are routinely flagging for mods when we see them in the delete pending queue. If there are still good answers leaking out this way then it's strong argument for your merge feature, or more diamond supervision of the delete queue. A diamond can always lock a question closed for deletion to preserve good answers.
That leaves Subjective&Argumentative, NotARealQuestion, and OffTopic questions. I am very much with John Saunders on the appropriateness of deleting these, regardless of the answers. Failing to delete them just encourages more of them, and leaves the perpetrators with their rep and badges, and advances the apocalypse when a whole slew of the people who love subjective questions get 10K. If that happens, SO won't be a Q&A site any more. It will be a discussion site with a few actual questions struggling to be seen on the front page.
Yes, that's overheated rhetoric.
A thought in response to a comment from Lance.
Let's be blunt. One reason to want to delete S&A questions is their traditional role as rep-magnets. I, for one, would be more comfortable leaving them around on the grounds of useful answers if the process made them, ahem, retroactively CW, or otherwise zeroed out 'ill-gotten' rep from them. At that point, the closed status makes the point that they are not the preferred activity of the site, and the advance of the muppets is slowed.