These games are made for a completely different target demographic, this kind of game is made to invite new players to the main games. This game has the same role that the Pokémon anime had years ago with our (90s kids) generation, you start to like the franchise with something else (anime/cards in our case, this "intro" game nowadays) and eventually you find out there's a "NEW" game of the franchise you like (which is actually the 30th installment). This also applies to Pokémon GO players, I had three friends that started to play Pokémon main line because of GO, the three bought 3DS, and two of the fuckers already have Switch before me (one is actually a competitivefag today). PoGo has like 800 million downloads (
http://vgsales.wikia.com/wiki/Pok%C3%A9mon), if 1% of these buy Switch and Pokémon, we are talking about +50% more sell numbers (XY and SM sold 16M units). I won't use foul words, just think about it from a company perspective