it's not due to piracy, it's because they haven't made that many great games anymore
And all the NES games were keepers.
The ratio of good to bad games has always slanted pretty far towards the bad games side, I can name trash you haven't heard of for days if necessary.
Also to those claiming that by buying a DS you are then entitled to take all the games you please, just give it up. You're a pirate, I'm a pirate, we're all pirates to varying degrees. Arguing the potential impact on sales is one thing, but pretending that getting them without paying for them is legit, is quite another.
There are reasons why China didn't get the N64 (until that newer system Nintendo made came out there in recent years) or the PS2 initially. The companies would lose so much money in piracy it wasn't worth it. (Take SNK who learned their lesson rather early, releasing "Art of Fighting" only for it to be hacked and emulated and playing in arcades as "Fit of Fighting" or the current King of Fighters Special ++ versions running in arcades in Mexico.) SNK probably took it the hardest, because up until very recently their entire library was fully emulated, which made it hard to sell games. (Arcades often ran emulators that played the games, illegal yes, but not many are about to blow the whistle on cheap games.) There still are places where you can buy MAME cabinets filled with, most oft, roms that haven't been properly licensed from the developers. (It's why Kawaks developers originally attempted to halt support for recent games, only to have hackers create add.dats that allow you to play everything up till the death of neogeo format.)
Now I make this argument in spite of the fact that I'm currently awaiting a Magic Swap for my PS2, but it's because I realize my position, I'm contributing to piracy, and I'm not making silly distinctions. (The one most oft heard is "It's too expensive", when most studies show that this isn't all that more expensive than previous debuts of systems. Take Triple Play Baseball 99, the thing sold for
80 bucks for a little while for some reason that still escapes me. New technology has always been notoriously expensive, my parents first VHS player for example costed $1000 easy, since it was new tech. I don't even want to speculate on what tapes costed then.)
Nintendo and SNK are really the only companies that have had to face their tech being emulated while it's still there current generation.