The downside of electoral democracy, is if you are only going to be be in power for 5-10 years max, why care about the state of the country in 30 years time, except out of the goodness of your heart? And electoral politics often does a rather poor job of selecting leaders with goodness in their hearts.

Of course, non-democratic systems have their own, equally serious downsides. Consider China: a system which is arguably much better at making long-term investments in public infrastructure than most democratic countries are (witness China's high-speed rail system), but also a system which ruthlessly suppresses dissent and locks up over a million of its citizens in "re-education camps"

>This makes me sad. The entire point of Government is to be an enterprise spanning multiple generations.

Not in a democracy. The point of a government in a democracy is to serve the current will of the people. The government itself might last many generations, but its goals and motivations change with every election cycle.

Even without politicians, the effective limit to most enormous projects is a human life span. Even if you look at projects that spanned 100-200 years like some cathedrals, they tended to be built in chunks: the main hall might be the first and largest, but things like trancepts, side chapels etc. would come later