Why not?
* If these consoles have no more utility, people will throw them away, and they will end up in a landfill. When this happens, they will want to buy a new console to play new games, and Nintendo will sell it to them.
* With more consoles in the trash, there will be less circulating in the world, creating a shortage and inflating the value of old IP. They can profit off of this by re-releasing or re-mastering those old games on new consoles (until those too are deprecated and the cycle repeats)
* Nintendo is taking actions to deteriorate the utility of peoples' old consoles. They do this by halting development of new games for it, shutting down online services, and shutting down digital sales of games.
* Nintendo is funding a lobbyist group that is fighting to prevent consumers from modifying their hardware to extend its useful life
* If people are allowed to jailbreak their console, a "homebrew" software community may take off, which could lead to customers willing to pay money for software by third party publishers; aka, competition for Nintendo within their own walled garden.
Based on those observations, it's obvious what Nintendo's position on the issue is. The path of least resistance and most profit is to encourage (or force) customers to throw their old consoles away and buy new ones.
Maybe they don't care if it specifically goes to a landfill, but they certainly want it in the trash.