I don't really think the DS's golden age was Nov. 2004 -> whenever it became apparent the Wii was going to be incredibly popular (which was almost immediately, right?). I'd say a lot of good games came out between 2007 and now. It definitely slowed down in 2011, but even it wasn't so bad. Ghost Trick, Professor Layton, Pokemon White/Black, Dragon Quest 6, Kirby Mass Attack and Radiant Historia all came out last year and they're all at least good. Some are incredible, like Ghost Trick. There's probably a few lesser titles or DSi games I'm missing. Aliens Infestation and Mighty Milky Way are both probably good (being that they're WayForward games), but I haven't played them.
And keep in mind it's a little over 7 years old at this point and its successor is on the market. It's a little unfair to expect a massive push behind the console.
Edit: I had a dig in my brain to try and think of what came out for it in 2010.
999, Etrian Odyssey 3, Dragon Quest 9, FF The 4 Heroes of Light, Unwound Future, Shantae: Risky's Revenge, Pokemon HeatGold/SoulSilver, Picross 3D, SMT: Strange Journey, Ace Attorney Investigations (which wasn't as good as good as AA1-3, but I wouldn't call it bad). Those are all pretty good games, man.