Even though the industry is practically obsessed with sequels, Pokemon remained one of the few franchises that didn't dip its toes into those waters. Well, until Pokemon Black and White 2, the first direct sequels in the Pokemon franchise (unless you want to get technical on Heart Gold, but let's not go there.) Why now? Why not go with their tried and true third color, or even just a new entry altogether?
In an interview with Gamasutra, Game Freak producer Junichi Masuda talked about why Pokemon went with the sequel route for once.
When creating a sequel, with this sequel in particular, we thought about what we could do to make it new, and why we need to make this sequel. And there are a variety of reasons, but in terms of gameplay, we really wanted to enhance the communication features, and really expand on the various communication features that connect players with other players. We really focused on making these functions even deeper and more in-depth in the game.
Another aspect is that when we have the two original versions and then a third version, that's very interesting in its own, but by having two versions this time as the sequel, we're able to kind of communicate in four different directions rather than just three. So in terms of the gameplay communication, we're able to expand in more directions than we have in previous Pokémon titles.
Another aspect is also the Memory Link, which when you're someone who has transferred a save data from Black Version and White Version to Black Version 2 and White Version 2 there are some certain scenarios or story elements that get unlocked, and are very interesting for players who've played the previous titles.
Whether or not the new Pokemon games achieve these aspirations, well–you'll be able to access that yourself come October 7th. So far reviews mention that there are vignettes that reference previous actions if you played the first installments. Remember, though: you don't need to have played Black and White to jump into 2!
(And I guess it makes sense that they didn't go for a third color, cause what would it have been? Gray? Not an appealing color!)