In any past year any unit/person/verhicle could reach any part of the world (expect perhaps of the poles) within 1 year.
We'd have to get rid of any movement point to make civilization 'realistic'. But civ isn't supposed to be realistic, it's supposed to be a good strategic game. And with strategic games it's important to make strategic moves.
Apart of that I totally agree with you, civ could use some changes in it's core game.