It's outdated. When it was originally put in place it may have shifted the power of votes slightly here and there but now someone in Wyoming has way more power than California. The other thing is ththe system was designed when states still wanted a small federal government that mostly let the states do what they pleased. That isn't what happens anymore. One person, one vote.
I suppose the elimination of the electoral college could have several positive effects. As you say one man one vote I would imagine would increase voter turnout. It's very easy to be apathetic about voting when you live somewhere with a pre-determined outcome.
I'd also suspect it would eventually encourage more third party candidates. Not sure if either party would be happy about that though.