>>30982797The thing is that they DID give the other starters attention... but they obviously gave it to the most popular of their lines.
You'll see Chespin in tons of media and Merchandise, and you'll also see Braixen in just as much of it. But that's because they're the most undoubtedly popular, unlike their final forms. You can't blame GF for giving the largest demographics what they want.
Imagine going to some place like Olive Garden and DEMANDING the entire chain of restaurants to add Kelp Chips with Grasshopper filling to the Minestrone because "you and 7 other people in USA like it that way". You think they would actually do that just to make you happy? No. They will continue serving stuff that they KNOW is tried and true, because they KNOW it has mass appeal and that they'll please a majority of people with minimal expenses and/or risks.
They won't go through the pain of making mass-merchandise and media appearances for Chesnaught and Delphox because they know they could make a LOT more people happy by doing that to the line stages that most people want, which is Chespin and Braixen. Same goes for Froakie, Frogadier and Greninja. There's lots of people (like myself) that prefer Frogadier over Greninja, but Greninja is so damn popular that it would honestly be stupid to put the same expenses on Frogadier.
Not everyone wins in the end, and that's ok.