As we approach election day, there has been the inevitable rash of pieces about the electoral college. The majority of the ones that I've read suggest that the EC is an archaic compromise from the early days of the country that was necessary to get the Constitution ratified, but that there is no longer any need for it. (Some of the alignments on the different sides of that compromise were not as clear-cut as many history classes make it. Georgia, for example, was a small-population state at the time but had large "western" land claims and anticipated rapid population growth, so backed proportional representation.) I'll take the opposite side of that argument. Not only are some of the initial reasons for the EC (and the Senate) still in place, but new ones have emerged as well.
The types of agriculture that are emphasized in
federal policy are regionally concentrated in the Great Plains, the
Midwest, and the South. Most of current federal ag policies originated
in the 1930s as part of an overall package intended to keep rural states
from falling into a permanent second-class economic status. The package was
created largely with the support of the more urban coastal states.
Without the leverage provided by the Senate and EC, rural states have
(at least in their own minds) reasons to fear that they would be put
back on the path to being second-class.
For the first 120 years or so of US history, one of the federal government's priorities was to transfer its public land holdings to private or state hands (see state land trusts and various homestead acts). That policy was changed around 1900, and the federal government decided to retain its holdings (a policy change that was eventually stated formally in the Federal Land Policy and Management Act of 1976). Today, the large federal land holdings are heavily
concentrated in the West. States in which a large portion of their area
is held by the federal government have a long history of distrusting the
federal government's management of those areas (with some historical
justification). In large part due to the leverage that the Senate and
EC give those states, they have been able to insist for the last
half-century that the Secretary of the Interior, who oversees most of the federal lands, be from a western state*.
Federal policy regarding regulation of coal-fired electricity generation provides yet another example. Ten states sued the federal Environmental Protection Agency a few years back in a (so far successful) attempt to force the EPA to regulate CO2. Of the ten, coal makes up a small part of electricity generation in eight. In a separate lawsuit a few years later, 14 states sued the EPA over its newest rules regarding particulate/NOx/SOx restrictions. In most of the 14, coal provides a large share of their generating capacity. States that are heavy coal users for historical reasons fear that other states will be able to force them into making expensive changes in their infrastructure.
The original Senate/EC compromise dealt with the fears of states with small- or medium-sized populations that federal policy would be determined by a small number of heavily-populated states. There continue to be issues where that same fear exists today. It is highly improbable that the US Constitution will be amended to get rid of by-state representation. The EC may be circumvented by state statutes such as the National Popular Vote Interstate Compact, but so long as amendments are voted on by states, the EC isn't going to be abolished.
* This may change. Following the Deepwater Horizon oil spill in 2010, the question was asked, "What does a westerner know about deep water oil and gas production on the federal lands in the Gulf of Mexico?" If there is a perception that the important federal holdings are the offshore Atlantic and Gulf regions, the western states may lose their leverage.