The Transformers Classics introduction in 2006 was probably the real beginning of what we know today as the ongoing Generations series. The idea of remaking Generation 1 characters in a modern style allowed Takara to design toys with more articulation and functionality that we had before. This allowed toys such as the Seekers and Optimus Prime to be improved greatly over their original Diaclone derived designs.
Today's Optimus Prime shot is all about the scale. When it comes to Giant Fighting Robots, size definitely matters. When it comes to collecting there is much joy to be had in the different scales of figures both bigger and smaller. The 2004 Transformers Classics Optimus Prime is a great example of how things have moved up and down from the Voyager class figure. Shown left to right is the oversized 2017 JuJiang JJ01 Supreme Leader (leader), 2017 Fansproject Parallax TFX-06 Red Armor upgrade kit (ultra), original 2006 Classics Optimus Prime (voyager), and the 2009 Kabaya GUM Henkei Convoy Model Kit (legends) figure.
The scaling is really interesting and pretty dope! I like the bigger and smaller figures. The figure after the smaller one is also cool as well.