Eh, honestly... I don't see how Nintendo is providing $20 worth of value to the consumer. From what I've seen, here are the features that you get...
1. Online Matchmaking: There are two issues that I tend to have with forcing people to pay for online play. First, if the game uses peer-to-peer networking for gameplay, the server load is incredibly minimal given it only handles matchmaking. I don't know how Nintendo's games work. Second, the payment is required regardless of who handles the servers. For example, why do I have to pay Nintendo to play a Capcom game online if Capcom is handling the servers? (To be clear, these issues aren't limited to just Nintendo's online service.)
2. Free NES Games: I don't mind "free games", but offering low-cost Nintendo games isn't exactly a huge draw compared to how Sony and Microsoft offer games for all platforms. I think the only advantage for Nintendo is that they are offering you a library, and you can just play whatever. For Microsoft and Sony, you have to "buy" the game during its freebie month. Although, we don't know how the library will change over time (add titles, swap titles, more consoles, etc.).
3. Save Uploading: This is probably the one good feature, but then again... to put it in rather simplistic terms, it's Dropbox for the Switch that doesn't even work on every game.
I'd be much more lenient toward paying for online services if it always guaranteed dedicated servers for #1. It's also hard to really put a lot of value in #1 and #3, because PC gaming has had these for free for years through Steam. (Albeit, not all games support Steam Cloud -- the save upload service -- either.) So, the only real cost-plus benefit that you get on all three platform is the free games.
I'm not a big fan of all the retro or old school games at least not many. I'd rather have them make new games instead. But compared to $60 that psn + costs, $20 is considered a bargain. I do play online with friends on the ps4 so I pay it. But the switch I got mainly to play on my own and to experience the games I've missed out on in the past years.
I usually only pay $40-45 for PS+. I think I'm good until 2020 at this point.