I ask this question because at first glance I find the idea of my government having a vision quite appealing. In fact, I may well have an unconscious assumption that it should or does.
But as I think about it a little more, I find the concept troubling. For example, when I think of well known political visionaries, I don't like what I come up with. Caesar had a vision (he came, he saw, he conquered), Mohammed had a vision (as Osama will tell you), Hitler had a vision (nothing much - other than world domination and ethnic cleansing), Mussolini had a vision (well, the trains did run on time), Marx had a vision (and I don't mean Groucho), Stalin had a vision (but at least he helped us beat Hitler), Saddam Hussein has a vision (though things aren't going well for him at the moment), etc.
There seem to be very few leaders who: (a) had a positive vision (b) were able to effect significant change toward that vision; and (c) the vision actually turned out to be significantly positive in retrospect. And most of those leaders appeared in time of crisis. There are some notable exceptions, of course. There really was no serious crisis when the founding fathers of the US got together, they did effect positive change, and I'll bet the outcome will be a political case study for millenia. But even their vision involved war.
Secondly, I think I prefer the perspective of the government working for the populace. I don't think the leaders of the country, state, or community necessarily need to be in the government. Many people complained when Clinton frequently used polls as a significant input to his policy decisions, but I actually rather liked that. I think our president and other elected officials should ask us what we think. That's not to say they can't lead at all. The president can use the bully pulpit to try to convince us that some policy is best. But if we still don't like it, he should listen and not do it.
Lastly, I would like it if the President had a vision that matched mine. But I would hate it if it didn't match mine. And I'll bet that more often than not, the vision won't be something I can buy into. As a result, I think I'd rather that the government stay out of the vision game.