What is the case for the electoral college? I'm familiar with the pragmatic arguments (a national recount would be a nightmare, voting fraud in one municipality could have a massive effect, etc.), but what is the principled reason why an electoral college is superior to a national popular vote?That's a good question. I'm mildly in favor of the status quo on the electoral college, mainly because I think the case against it turns out to be fairly weak.
The strongest case for it, I think, is that historically the biases it introduces tend to be somewhat different than the biases involved in the rest of the system, and so using the EC method for presidential elections has tended to bring some balance. In particular, the malapportionment of the Senate, and the traditional malapportionment of House (and state legislative) districts until about 1960, meant that urban areas were shortchanged in Congress -- while the big, urban states traditionally did very well in the electoral college. As it happens, however, that's been much less the case recently. Remember, New York used to be a major swing state; California also was very contested once it became large, and even Texas had a run as a competitive state with big cities for a while. For whatever reason, all of that has slipped some over the last twenty or thirty years, which in my view makes the electoral college less worthwhile.
Still, all else equal, a presidential candidate would rather pander to a large state with lots of winner-take-all electoral votes than a small one, which should tend, over time, to balance out the small-state advantage in the Senate. So in terms of a positive case, I'd probably emphasize that.