You have a touching faith in the intellect of the electorate.
But the truth is the electorate are not ready to forgive the last Labour Government, and Ed Milliband has neither the beginnings of a manifesto nor a credible front bench; the Tory vote is holding solid and the bill that provided for the AV referendum also provided for boundary changes in the Tories favour; and the Labour vote in Scotland has collapsed, and Labour have always relied on Scotland to deliver a majority.
Cameron can call an election any time in the next four years and get an overall majority. If the right of the party and their backers in the press has any say in the matter, it will happen sooner or later. And then the fun really starts.