It's a way to keep balance between big urban centers and rural areas. If all that mattered were the popular vote, candidates would focus solely on major population centers; big cities. I'm sure people in rural communities would be upset if they were so underrepresented as a demographic. Then again, you don't want people in low-population areas to have a disparity of power per vote as compared to people in high-population areas either. You need balance. The electoral college provides some semblance of that.
Realisitically, it could be improved, particularly if it were done by county/district rather than how most states do it, a popular vote for all the electoral votes that state has. But that still has a way of amplifying the voting power of rural counties, so it's not a perfect solution either.