voice chat is difficult and terrible, so nobody really uses it! that's a major plus in my book. most people will never run into more vile people than when gaming online.
the multiplayer is unbalanced, issues with lag and disconnection often mean that the outcomes of matches just aren't fair. this is good, because it sort of limits how seriously you can take the game. just relax and have fun instead of a hypercompetitive 3-hours-a-day online sport.
the inconvenience of parties/team up is good, it means it's hard for people to get an us-vs-them mentality or want to just dominate weaker players.
i'd be really shocked if this is all intentional on Nintendo's part; it's probably just hubris and not-invented-here syndrome.
but in practice it feels almost like all the online inadequacies are a kind of traffic calming -- like putting trees and islands in the middle of a busy road to get people to slow down. it makes things more welcoming for people like me who normally loathe online games.
The lack of voice chat is no problem for me, though the app is terrible at what it tries to do (voice chat with your own team) which is something I'd want to do with casual friend players. Instead I just end up using Skype.
The touch screen and the the Joycon accelorometers/advanced rumble aren't used at all in many games, or if they are, it isn't anything innovative. ARMS is an exception, though, but I really don't think many people bought the game.
The Mii avatar you create can't do much of anything. On the Wii U, Wii and DS there was a bit more you could do with those.
Amiibo aren't really useful except for small in-game bonuses
The companion app is currently lackluster. They could have made a Mario Kart 8 section where you compare your scores to your friends, a BotW section that would interface with your game... for now it's just a Splatoon app with a few nice features, with only one main feature actually communicating back to the game.
I guess those middle two aren't Switch-specific, but there are a lot of Nintendo-specific things that they should really considers spending time cultivating.
It's especially nice in handheld mode, where the user doesn't have a decent speaker system to emphasize things (and may not even have the sound turned on at all). In those situations, the user may not be able to hear the sound effect when they get hit by a shell or drive off the road. But with the rumble, the punch of it is still there.
Nintendo also shed beloved handheld features like Streetpass, didn't include obvious features like Bluetooth audio, and are really messing up their online services ... the internet Splatoon fanbase seems to roundly regard the Switch online experience a failure for the context of 2017