Thinking about it, to be fair...
2013 - Pokémon Rumble U
2013 - Pokémon X & Y
2014 - Pokémon Battle Trozei
2014 - Pokémon Art Academy
2014 - Band of Thieves & 1000 Pokémon
2014 - Pokémon Omega Ruby & Alpha Sapphire
2015 - Pokémon Shuffle
2015 - Pokémon Rumble World
2015 - Pokémon Super Mystery Dungeon
2015 - Pokémon Picross
2016 - Detective Pikachu
2016 - Pokkén Tournament
2016 - Pokémon Comaster
2016 - Pokémon GO
2016 - Pokémon Sun & Moon
The last few years have been very busy for me
That said, this wasn't at the beginning of the franchise...
I think the Yokai Watch drop has many reasons... i don't think Spin off are the main reason.
I'm not really sure honestly... what i am sure is that Pokémon is another planet. It won't drop so badly soon, if ever.