It's precisely because without the electoral college, small states would receive zero attention on national politics.
Why would anyone spend time courting votes anywhere north of New York when there's a much bigger payoff to be had working the rest of the eastern seaboard and the west coast?
To use your examples of Massachusetts and Ohio, why waste time on a campaign stop in Boston when you can hit Columbus? Columbus has a much larger population and one can also hit Detroit and Indianapolis in the same day to maximize their face time with the public.
Going to a popular vote will have consequences that people really need to thing about.