I think you wildly underestimate who purchases these consoles. There is certainly an element of catering to a younger audience, but young adults are the real money maker.
In my experience, at Pokemon release events in Japan and in the United States, the majority of attendees lining up are adults, most under 30.
What you’re describing is Nintendo reaping the rewards of having previously targeted kids. If you play a modern Pokémon game with a non-nostalgic eye (as it is easy for me to do, since I am too old to have grown up with them) you can see that however fun these games can be for an adult, they are definitely made to appeal to children.
This is definitely true. I had a SNES, but skipped the N64 and also for some reason never played Pokemon as a kid. It's still reflected in what Nintendo games I like. Zelda a Link to the Past was my favorite game. So I loved A Link Between Worlds. However, I really struggled getting into any of the 3D Zeldas because of lack of Ocarina of Time nostalgia. Same with 3D Mario games. I bought Pokemon for 3DS during a lot g layover on my first trip to Japan. I thought this would be the perfect drosetup to get into the series but without nostalgia it's too easy, to repetitive and I honestly saw no reason to get more than a handful of Pokemon.
Planting the seed early and reaping rewards for the entire life is definitely what works for them.
Funny enough, I like the Shin Megami Tensei series which in essence is a dark and challenging Pokemon. I find the mindless grinding while listening to a podcast quite relaxing.
Those 30 year olds likely fell in love with those franchises when they were kids. i suspect Nintendo know this and see catering to kids as an investment.
In my experience, at Pokemon release events in Japan and in the United States, the majority of attendees lining up are adults, most under 30.