Uncle Bob, I'm not saying there isn't a reason Nintendo is the way they are. Clearly, they built the modern console with the NES and enjoyed a strong monopoly early on. The SNES was a very solid system, cutting off at a top 10 is a bit harsh. The top 30/50 games enjoyed strong success on the console. Also, there were fewer developers back then. Square, Capcom, Techmo, and Konami all gave the system exclusive support. Yes, some tried to develop for the Genesis, but the Genesis was really on strong in the US and Japanese developers supported the SNES better since it sold way better in Japan.
I guess I feel like this is a good summary of Nintendo. They built modern gaming. DK, Mario, Zelda, Metroid, Goldeneye.... Most games are built from them. They enjoyed early success and consumers loved them. But as competition entered the market, Nintendo has continued to lose market share and turned away from their customers. No company can have long term success if the focus isn't on the customer.
Nintendo (N64), gamers don't want bigger games (discs)
Consumers that want bigger games move too Sony
Nintendo (Gamecube/Wii/Wii U), gamers don't want third party games
Consumers that want third party games move on to other systems.
Nintendo (Wii), gamers don't want HD
Consumers that want HD move on to other systems.
Consumers want to save $ on a console, not a powerful console (Wii/Wii U)
Consumers that want great graphics/great physics move on to other systems.
They aren't listening to their consumer base and consumers are choosing other products. You look at lists of most popular games now and it's flooded with games that aren't on a Nintendo console.