I respectfully disagree. In Civ I, leaders were hardly ever seen. You waged war against Germany. In Civ V, you wage war against Bismark. The games have moved from portraying civilizations to portraying leaders.Leaders that don't age, the talk of tile improvements and terrain benefits in warfare are the hallmarks of the series and may apply to almost any game in the franchise.
All the more so, leaders used to change as time changed. They'd wear different clothes as time passed. In V, they always appear the same way. Napoleon is on a horse when he's still in the Stone age and hasn't tamed a cow.
Leaders used to age. They changed aspect as their civilization evolved, were part of thier civ, now they are decorrelated, things that live outside their time. Worse, they all behave like opportunists who stab whoever was born on their continent, unlike IV. They are so predictable that they feel more like mathematic formulas than IV leaders ever did, despite their showing of numbers in diplomacy.
The difference between improvement and warfare is not that off either. Buildings are so very long to build in this version. Wonders are so not wonderful. And I still miss caravans from civ 2 to make trade as fun as warfare.