Questions about the need for fiscal rules

Over at Stumbling and Mumbling an interesting question;

Which raises the question: why do we need external rules to do this? Why can’t the electorate do it? Younger voters should see that big borrowing is merely deferred taxation, and punish governments for imposing it. And older voters who care about their children and grandchildren should also punish governments.

So why don’t they? One possibility is that our electoral system is just too clumsy to permit them to express their discontent; we are only ever offered a choice of job-lots of policies, not individual ones.

Another possibility is that, for all our drooling and drivelling, we as a nation don’t actually care about our children.

Whichever it is, let’s be clear. If we need fiscal rules, it is only because of moral and/or political failings. But are technocratic constraints really an adequate substitute for adequate political structures or more sophisticated moral sensibilities?