but surely this is simply not good enough for fans who want to have AAA games with that Nintendo magic.
Strictly talking about what was shown in the Direct relative to what we know are in the works (Bayo 3, BOTW 2 etc.), you are right. It's not enough and Splatoon 3 is the only real heavy hitter in the first party titles shown.
Both Microsoft and Sony are bending over backwards buying studios if not entire publishing companies, signing developers for exclusives, putting millions into bigger AAA first party games, and here we have Nintendo just sitting there making Mario Golf, Splatoon 3, and pretending that it's enough.
While I subscribe to the belief that successful Nintendo is a complacent Nintendo (I feel they tried much harder with software output on the Wii U than on the Switch), I think your interpretation errs on the side of bad faith.
That they would show Splatoon 3 even though it's slated for 2022 at a minimum shows that they know they need a big hitter to close out the direct, they're not completely tone deaf. And it also means none of the other heavy hitters have footage they're willing to show, for better or worse.
The reality is Metroid Prime 4 had developmental issues (and it is fairly well known), Bayonetta 3 isn't within their control, neither is SMTV. Only games we can slam them for are BOTW2 and whatever mainline Mario game they might have planned, oh and whatever games that Yabuki (Mario Kart, ARMS) and Takahashi (Xenoblade series) are quietly working on.
If they churn games out quickly, thus lacking polish, then there'll be comments of "Nintendo fans buy anything Nintendo shits out", even if the games don't sell well, as evidenced by some of the rushed games on Wii U when Nintendo had to fill in all the gaps that 3rd parties and indies now help out with.
Nintendo takes the time to polish things up and it's "Oh they're sitting on their arse pretending it's enough." Lol.
Good, polished games take time man. Look at Sony's first party output. Naughty Dog produced UC4, Lost Legacy and TLOUII (I'm not including TLOU Remaster but feel free to include it if you like) over the span of roughly 6 years.
Sony Bend produced Days Gone.
Sucker Punch produced Infamous SS, First Light and GoT.
Sony Santa Monica produced GOW.
In terms of each studio’s output averaged out over 4 years, they aren't exactly putting out many more than Nintendo, though the perception is there. (I'm aware there are other Sony first party games, I'm not gonna list everything). Point is, there's a limit to number of studios and games they can actually produce.
And then look at Activision and Ubisoft, who've managed to set up a production pipeline to churn out these large scale games on a 1-2 year basis. Guess what most of those games get called? "Soulless, cash grabs"