The big reason people dislike them is because 10-15 years down the line, Nintendo might not have the download options ect.
Meaning the key card becomes juist plastic junk, at that point.
However the counter argument is this: https://www.youtube.com/watch?v=wY16S5x3dHc
The same thing happens with games that are on the Cartridge as well.
New firmware makes it so, you cannot play a offline game, if your system knows that there are patches to it, without updates.
Essentially bricking the game, if you cannot download the patch (which 20years down the line, you might not be able too).
*edit:
This is bad for game preservation.
Afaik, Xbox does the same thing.... I think only the PS5 of the 3 consoles actually values allowing you to play a game, where you have the intire game on disc, if in future say there is no way to download patches ect.
