What's wrong with a 'hung parliament' if that's what the electorate votes for?

After his party has lost three consecutive general elections and spent thirteen years in opposition, Conservative leader David Cameron has started to issue dire warnings about the horrors that await us if we're stupid enough to vote for a 'hung parliament'.

I'm as flabbergasted by this as I was by Labour friends who continued to denounce proportional representation during their eighteen years in opposition between 1979 and 1997.

So my three questions to both the bigger parties are the same:

1. How does your party (not to mention the poor old country) benefit from your preference for letting the other lot do whatever they like for 13 or 18 years when you could, with a more rational voting system, be in a position to moderate and/or restrain the excesses that inevitably flow from absolute power?
2. Is your party quite happy to be powerless for a decade or two in exchange for being in power for another decade or two?
3. Could one or other of you please explain how anyone in the country actually benefits from this bizarre form of turn-taking?