Probably is just a changing of the guard from the old EAD era of Miyamoto/Tezuka-era Nintendo, but Splatoon and ARMS feel quite different style-wise from Nintendo's 80s/90s/early 2000s creations. 

Flash forward to today though ...

Definitely much more uh ... contemporary I guess? Splatoon definitely taps into snowboarding/hip hop/j-pop/2000s-era culture I would say with influences from areas in Tokyo like Harajuku and Shibuya. ARMS looks straight up like a late 90s/early 2000s Sega arcade game. 

Kinda interesting I guess. I think this is the influence of younger designers at Nintendo, whereas the older guard at Nintendo like Miyamoto/Tezuka etc. looked up more to like golden/silver age cartoons, Disney, and classic anime, etc. 

Yup, it's just the fact that fresh blood and talent is entering the company. A natural progression if I've ever seen one. The benefit is, the younger generation has a pool of older ideas/ art styles to pull from once they feel their work is becoming stale. It's a never ending cycle. But man...Twintelle... she on a whole nother league. I can't believe Nintendo okayed this thang ALMOST puts Onion to shame.

Nice view of Twintelle

we need more pictures of Onion, to compare, lol

uh....Samus?

Pretty much.

Samus ain't got sh#t on Twintelle. Don't even play.

Whaaaaaaat? You crazy!

I think he is specifically referring to Nintendo EAD / EPD. Their internal developers. F-Zero GX was actually developed by Sega so you're sort of proving his point.

Soundstage used no Fire Emblem, Kirby, Pokemon characters as examples for a reason.