Ever noticed how odd-numbered generations are the "main" ones while the even-nubered ones are more like "complementary" ones?

By main ones I mean:

>More pokemon added (~150)
>Not many evos or pre-evos of old pokemon added
>With the obvious exception of gen 1, "remake" pokemon (pokemon that are not only very similar to older ones but also have the same "roles" they had) are common. Some examples: Beautifly(Butterfree), Corphish(Krabby), Spheal(Seel) in 3rd gen; Woobat(Zubat), Bouffalant(Tauros), Audino(Chansey) in gen V

And by complementary ones:

>Less pokemon added (~100)
>Many evos and pre-evos of old pokemon added (Just look at gen II and IV, and notice how all even-nubered gen added eeveelutions)
>"Remake" pokemon are scarce, new pokemon seem unrelated to old ones

The fact gen VI will only add a little more than 100 pokemon and seeing how many new evolutions/forms for old pokemon it has only comfirms this pattern.