This.  Plus the fact that if the price doesn't drop, you aren't being screwed over by buying on release day.  The number of times I've seen the phrase "I'll wait for the price to drop" on this site.  If you want to sell your game at $10 then sell it to everyone for $10....

But they do sell... just look at the top 10 lists.. you'll find Nintendo games that came out 2017-2018 on there

Different business approach Nintendo relies more on on the returns from software than other companies it also ensures that the games recoup costs and create profit, case point you mentioned Sony guess why their first party titles are beginning to appear on PC those bargain bin prices aren't paying for the game's development despite the sales numbers being good.

Long post.

For most AAA publishers (incl. Sony), the core value proposition of a new game in 80-90% of cases can be narrowed down to novelty: new story, a larger scope compared to the previous entries (meaning a larger world or new systems being added on top of pre-existing ones), graphical and technological advancements compared to previous entries.
Novelty has naturally a very high value at launch, but then it will degrade quite quickly because other developers will introduce other new games with even grater scope and with even more technological advancements. Even considering two entries in the same series and from the same developer, the the sequel in most cases will offer better production values, meaning the previous entry becomes obsolete in comparison. In this sense discounts reflects the game being outdated.
Also, form a publisher perspective, selling an old game in a bargain bin means giving it more exposure and by extension meaning more people are likley to buy its "shiny" new full-priced sequel. It's a marketing investment to a certain degree.

For Nintendo, their core strategy is trying to create a unique value proposition with each new game . This means with each game must posses some differentiating feature to set it apart from both other games in the market and also form its previous entries and sequels. You can see this very clearly looking at mainline 3D Mario and Zelda series, each game is market with a particular theme and a particular gameplay style.
Zelda example: Wind Waker (waterworld; saling / sea charting); Twilight Princess (wilight word; switch dimension / metamorphosis); Breath Of The Wild (open air; free exploration).
Mario: if Nintendo operated like any other publisher Sunshine would have been a Mario64-2 kind of game with the same core concepts, new larger levels, some additonal features and better graphics. Instead Sunshine is a game with a very specific theme (tropical island) and a very specific playstile (fludd water spray and jetpack) and those elements weren't replicated in sequels.
This is the reason why they don't drop prices quickly, since "uiniqueness" is much harder to degrade of over time. Since there are no other similar experiences in the market to this day (form both other devs and Nintendo itself) a game like Mario Sunshine or Mario Galaxy remain equivalent to a new game for a person who hasn't played them.
Counter example. Take Uncharted 2; the only element of the game that remains truly unique of the experience to this day is the story. Any other element of its core design has been reproduced and improved over the years by both Naughty Dog and other developers as well. To a new player it's not a fresh experience anymore.

To be clear, I'm not saying Nintendo's strategy is good and the other is wrong. They are just different and each have their own advantages/disadvantages.

I was ging to write a reply about different business strategies, about customer's expectations as well as customer's perceptions of value but then I saw the posts of Otter, TheBraveGallade and TomaTito and they all nailed it, so I'll just promote their posts instead because they are excellent.

Have you ever heard of "Nintendo Selects" ?
It will eventually come to the Switch as well

Just my 2 cents but... Nintendo is a videogame-only company. It's the ONLY WAY they make money. They simply can't afford to drop their prices all willy nilly.

I hear your logic here but I disagree with it being the reason for difference in legs and/or prices. Beyond natural gameplay and graphical evolution what is the differentiating factor between Mario Kart Wii and Mario Kart 8, or NSMBWii versus NSMBU deluxe, Or Smash Bros Brawl vs Ultimate? These are the titles that would pull the biggest numbers historically.

The reality is there are so few cases where Nintendo will actually have sequels on the same platform that this argument cannot really be made as you intend to make it. Scarcity is what creates the value, when Nintendo do create sequels on the same platform we've seen they perform worse. Mario Galaxy 2 didn't make Galaxy 1 enter the bargin bin, but it did sell notably less then the first. Same with Ocarina > Majora, Twlight Princess > Skyward Sword and I'm sure we'll see it with BOTW vs BOTW2. The notion of scarcity has to also be tied to the fact that we're talking about 8 or so titles per generation when discussing Nintendo's longevity. The vast majority of their output simply does not sell high volumes beyond its release year regardless of how unqiue they are, and would absolutely be receiving price cuts if handled by another publisher. For example from last year Luigi's Mansion 3, Astral Chain, Links Awakening, Fire Emblem, .. but they are all still full price despite significantly slowed global sales. 

Also worth noting that BOTW and Odyssey sales are not normal for either franchise. Per platform Zelda has always been under 10m peaking with Twlight princess Wii  (8.5m) and Mario only ever passed above 10m with Galaxy 1 (11m) and 3D World on 3DS (12m). So a really interesting discussion would be what caused those sales to explode this generation. Equally what is it about Nintendo's other ever greens (mostly multiplayer bar 2D Mario) that causes them to excel where their genre peers struggle? I think the answer may actually just be brand recognition (particularly anything with mario in it) + seal of quality. 

Part of it has to be competition.
Nintendo Switch has sold ~400m games.
PS4 has sold like ~1500m games (I think?).

Even if you account for the fact that the Switch is only been on the market, half as long (and double Switch game sales to compensate) you notice its still like half of the playstation 4's.

Basically they sell alot more games, thus theres more competition for the 1st party games.
Also 3rd party are more aggressive with price cuts too there, so Sony 1st party follow suit.

Meanwhile, alot of Switch owners, also own PS4/Xbox's and usually arnt as intrested in 3rd party games on that system (if they already own the games on other systems, or plan to play them there). So the main draw of the Nintendo system is its exclusives by far (more than the other platforms).

Nintendo knows this, and thus keeps prices high on their games to profit more.


Also it could be a differnce in mind set.
Some companies are fine, makeing small profits on each unit sale, but selling more, to accomplish the same.
(while others, are willing to keep prices high, even if they know it potentially means less sales, but since the price is higher, the profits are fine)

As a consumer, buying things cheap is awesome though.
Who doesnt love a good sale? Most people dont trade in / sell of their games anyways.
So the "it keeps its price" doesnt effect most people.

What does? buying good qualty games for cheap.
Its part of what makes owning a PS4 so nice.