But Nintendo, and I believe them, have stated and implied for years how they care about the physical and mental  health of their consumers. That's why we got games like Brain Games and devices like wii motion, wii fitness pad, and why they are working on other QoL improvements (including, according to rumors and patents, some kind of sleep monitoring device). They care about our health. If they think that something leads to an unhealthy obsession, then they won't do it. Heck, you can't even play their games without warnings (including pop ups) saying you should take a break after it's been like 30 minutes of play. They care like crazy about their consumers.

They commented on that a few years ago

http://www.gameinformer.com/b/news/archive/2011/01/21/nintendo-explains-why-they-don-39-t-do-achievements.aspx

I played smash 4 and xenoblade x which both have a similar achievement system and I also play in a little bit of Steam. My opinion on it? It is stupid. I do not really like being told how to play my game. I can ignore it yes but it does not change the fact that I want them in my games. Also some of them are absurd sometimes. I have better things to do than just play a certain way to show off I can do something. So I do not think it is stubbornness but rather Nintendo does not think it fits their games. Maybe it does not fit any game at all.

I think they're just mad because they didn't think of it first. Meanwhile they're only prolonging the inevitable since they WILL have to implement it one day.

Yes it is. Haven't you read all the interviews/articles with them stating that they didn't want people to buy them obsessivly as collectibles? They didn't envision Amiibo becoming like a pokemon card collection activity.

Nintendo cares for your health?.... im so sorry because they dont. They only care about money and making profit.

So on topic. Like others have said, they are stubborn.

I do not know much about Achievements. Do you get more than bragging rights for them?

EDIT:

Looking into it a little more. Let's take Halo 5 and Mario Kart 8 as examples.

Halo 5 has 65 achievements and earn a total of 1000 gamerscore. At least half of them are very simple like completeing a mission, spectate a game or change your Spartan's gear.    http://www.ign.com/wikis/halo-5-guardians/Achievements

Mario Kart has more than 65 unlockables. Most of them comes from completeing simple tasks. Each gives you a new kart or part. Additionaly there are unlockable modes, alternate ending credits and stamps.    http://www.ign.com/wikis/mario-kart-8/Unlockables

The thing that differs between achievements and unlockables, as far as I can see, is that achievements give you a number to brag about and unlockables gives you some kind of visual gratification (gears, stamps etc).

They aren't doing it because they believe there's better ways to add replayability and "fun" to a game.

And they're right. Achievements are shallow, are often like kicking in open doors and when not, tedious. I don't care either way though as long as I could turn them off and be about my business, but would definitely understand Nintendo in this case if they continue to ignore this. Personally I've never gotten the appeal and always thought it was pointless even from the very start, whether it be on PC, or consoles.

I'd stay stubbornness and refusal to copy others, but that never stopped Nintendo from ripping off Skylanders with Amiibos.

Then they are lying through their teeth, if your right, because I have never seen a company so consistently and for so long talk about quality of life improvements and initiatives in their products. Microsoft and Sony have certainly given no efforts to convince people that they are even close to as health obsessed as Nintendo.

And yes, Nintendo likes to make money, by focusing on the health stuff. Wii sports and Wii fitness sold link bonkers last gen and made them a ton of money while it made the rest of us engaged and healthier. Their pulse detector technology, fitness clip on, continuation of using the pad in the Wii U version, step counter in the 3ds, their sleep technology they are working on currently amongst other QoL things, their use of gyro technology in the Wii U gamepad which basically requires you to stand up while using, and other things all point to them actually caring about people's health and getting them moving around.