Just last year Suika Game, a third party IP, became the most downloaded Switch game of the year, beating even Tears of the Kingdom and Mario Bros Wonder.

The Momotaro games, also third party, have exploded on Switch in the last few years.

Genshin Impact, Honkai Star Rail, and Zenless Zone Zero were big hits in Japan too.

I'm talking about thirdparty developers that  actually make games for the core gamer and are known to be top developers. I don't even know what those games are.

So your issue isn't really "there are no big hits other than Splatoon in the last 10-12 years" but rather "how dare the Japanese not like what I like".

Are these games really even quality? They look like mobile games.

My issue is Japan is really starting to abandoned core gaming, you know the ones we mainly play other then nintendo games, and not games I like, it's games that are recognized as quality and big hits all over the world. I would put it like this if every region loved nintendo games and the US was like oh nintendo games are too kiddy that's how basically Japan is right now with anything that's not family friendly it's small market for those type of games in japan. 

This whole thing should have ended with this post.

I'm pretty late to this, but it seems you guys are just repeating the same thing over and over again. Sheesh I'm not sure where to start and I'm not planning to spend much time on each response. There's a lot I can say cuz there's that many misunderstanding, but I'll focus on the main topic. 

What's even considered "core gaming". Everything that's not Nintendo or mobile games? If so, this fixed concept from @zeldaring and many others are completely wrong. Just look at the top streamers, content creators in Japan for video games. I'm sure you guys don't know who they are judging by the conversation so I'll name a few.
Top streamers - Kato Junichi, Shaka, Stylishnoob, vtubers like Pekora ch
Top content creators - Kiyo, Pockey, Hikakin

Just look through their channels by googling them. You can see that they've been playing a wide variety of games. In fact, most of them plays more of those "core gaming" stuff discussed here. Just look at the games they are playing RIGHT NOW. ARK, Terraria, The last of us Part 2. Furthermore, look at the JP channels on Twitch right now, none of the top streamers are playing Nintendo or mobile. 

Ok, content side "core games" are much popular, but that doesn't mean they are popular there! Wrong. Simple google search proves that, like why Japan had some of the biggest Apex Legends community. 

You guys are only taking one data and forming your opinion with just that. It is true that mobile games and Nintendo games are big there, but that's not the full picture. Famitsu only reports console sales, and physical (very important to note). 

This debate is pointless in the first place. We are just arguing why something is more popular than other. What in the fecal matter is this low IQ conversation. Such a stupid discussion but I'm here to talk about it cuz why not. I can feel my last brain cells giving up. I guess it's not even a debate, just some complaints and whining and sometimes we gotta do that.

Yeah, as oppose to seeing this as any objective argument I would just skew it as @zeldaring mourning that the games that traditionally used to be very popular and dominate the market, are doing so less so now. It's sad, for them... There is no fault of the Japanese audience and seemingly no fault of Japanese devs either since they often find larger market oversee's now. It is, what it is.

Switch 2 will be interesting to see if it reignites passion for IPs like resident evil, FF and more traditional AAA/AA IPs.

Figured I had to comment on this thread, since it's the most popular one in years! Unfortunately not super fun to read through LOL.

Not sure why it matters to you whether those games are actually "quality" (which is a rich thing to be saying given how CoD, Madden, and FIFA dominate US/European charts). Not sure why it matters to you that the "Japanese likes the kiddy games". They consent, but you don't...and we're discussing what games they wanna play. Why does it matter to you? It shouldn't be viewed as "sad" when one culture favors a certain market of games which may not appeal to another. Whether this be Americans favoring shooters over Pokémon, or Japanese favoring Genshin over Call of Duty.