Yes, and if I were to swing a sword at a wolf. would I get a big yellow explosion of light or would I get visceral slice with blood pouring out from the wound? Compare the combat between BOTW and Skyrim and you'll see what I mean. It has nothing to do with 'flashiness'.

Not yet but it's getting better and Nintendo seem to be working on it.
Switch's marketing has been really great and i think games like Smash/Metroid/Fire Emblem/Bayonetta 3 coming soon and will be all over the media, that will help a lot too.
I just think it's the perfect era, they are listening to their fans and core gamers but still think about families and kids on the side so they can please everyone, which seems to be working.

Nintendo will always be known as the kid friendly company. Idk where you guys are getting this "adult" Nintendo from. Nintendo is targeting E for everyone, which in turn makes them unable to do more adult games such as Cyberpunk 2077 or Grand Theft Auto. Anyone who thinks otherwise is just being a biased Nintendo fan.

Wii did that over a decade ago.

I think Nintendo kinda attempted that with the GameCube, but that obviously didn't work, and considering how old the company is, getting rid of that perceived image in the eyes of people, mainly haters and non-gamers, will be extremely difficult, if not impossible.

It isn't a stigma I personally believe but it as widely accepted as things like a sports curse or other things in this world. 

Nintendo can't escape this, they helped distribution on the original Conker game, seem to be Co owners of the Fatal Frame franchise, plus various mature rated games over the course of various platforms. Yet anyone that needs an excuse as to why their game isn't on a Nintendo platform or why it didn't do as well can use the excuse of Nintendo being a 'Family' console, pretending the prejudice doesn't exist or can change won't remove it.

Not to mention let's be honest that stigma and the various IP that are used as examples of it helps them get into some households better then most other publishers.

I was a huge Nintendo fanboy growing up, owning all Nintendo systems. I never understood the kiddie image. They housed some violent games and even games that came out under there own umbrella like Conkers BFD.
I always took the kiddie image as just a jealous attack on Nintendo and there policies.

The Switch can't destroy an image that Nintendo dictates. The Switch, just as any other Nintendo console, is designed around children. Both the system and the Nintendo software offers show that. Of course there are some games that are not meant for children but that doesn't really erase Nintendo's intention. Nintendo wants to be the console for kids and they're working hard to make that obvious.

A better way to word what your saying is Nintendo aims for there systems to be for everyone. That includes children. Hence the measures they take. 

Nintendo's fan base is majority adult. That's just becoming a fact now.

The majority of people buying things like the Switch, NES Classic, SNES Classic, even Amiibos I would bet are grown adults.

Nintendo's demographics have shifted, people who grew up with the NES and SNES are now in their 30s, 40s even. But even people who were kids when they got a DS or Wii 10-12 years ago are today adults now. GameCube/N64 generation are in their 20s/30s. As generation after generation has past, Nintendo has amassed a growing and much larger adult fan base to the point where they now outnumber any number of 5-12 year olds that will be part of any generation for Nintendo IMO.

It's adult majority now. It happens in other mediums too ... at one time comic books were thought of things for children, but today probably 80%+ of comics are purchased by adults. Nintendo didn't have the same backing in the GameCube era, but they do today, enough time has passed and they've grabbed new fans every gen to add to the "lifers" they got from before that things are shifting.