1. Most people don't carry Switch's in their pockets/backpacks, so streetpass would probably not be used by many. 3ds's were very heavily placed inside pockets and backpacks, so you'd get lots of streetpass data.
2. I'd imagine those free mini games weren't that talked about or played, since we don't see them now.
3. While the themes/music seemed cool at the time, it gave Nintendo more of a "micro-transaction" image than they probably wanted. A LOT of companies get hated on for cosmetically purchasable content, and Nintendo more than most companies care about their image. Also, less money spent on themes = more money to spend on games.
4. I agree on the rankings, I loved that feature and miss it, but again try to think from their perspective. They have for years resisted achievements because they want people to relax and enjoy the games, not get obsessed with them. Maybe the data they had from customers indicated people were getting too obsessed and stressed about minutes/hours and they decided it was in the best interest of the health of gamers to stop having said feature. They have focused on health issues since the Wii days so this would not surprise me at all.
5. Miiverse was really cool, but they were constantly having to squash inappropriate content or divisive movements on it. They want that family-friendly image and that is hard to keep when your social media platforms is covered in genitalia drawings.
6. Wii Sports was huge on the Wii, but quickly dropped in popularity with its two sequels. Wii sports sold about 83 million, then Wii Sports Resort sold about 33 million (a massive 60% drop), then Wii Sports Club on Wii U sold (according to VGchartz) 0.38 million (a massive 89% drop in sales from Wii Sports Club and a gigantic 99.5% drop in sales from the original game). That kind of tremendous downward trend told Nintendo execs all they needed to know about how dead that series is. Could it come back? Sure, and I'd play it, but I doubt they will make another one.
7. Sometimes you just don't have the right personalities for numerous directs. I get the impression Doug Bowser is a lot less funny than Reggie, but I don't know for certain cause the guy is hardly ever in front of cameras.
8. Those ports they are charging full price for? They didn't have to port them at all. If the only way they could justify spending money on porting them is to have a certain return that can only be achieved by selling at that price point, then it is what it is. It would be one thing if the Switch was a huge graphical leap forward and they were charging full price for Wii U games that look so much worse than Switch games, but that isn't the case. Wii U = Switch graphics to most people who aren't hyper analyzing.
9. I think Iwata would have looked at the same data as the current leader and made the same calls.