Civ V completely redid movement. The prior games would allow you to stack units, so you'd end up with a 1-tile "stack of doom"; later-game fights would be reduced to these stacks of doom wearing each other out instead of tactical play. Additionally, making a unified front was difficult because of square tiles (a unit could move in 8 directions).
Civ V changed it so that only a single unit of a given type (military vs utility) could occupy a tile, and switched from a square grid to a hex grid. Individual moves may matter less, but the combat game benefitted greatly.
