If the game library is the only reason I say the point is moot since the 3DS can play DS games.
And most of them look like [parasitic bomb] on the system.
Simply, there are games developed for DS, there are games developed for 3DS (etc.) That's how I look at it.
Just because it has the capability of playing DS games, I don't give it extra points on the "enjoyment" scale.
Hypothetically, I won't play a DS game I've never experienced before, play it on the 3DS and go, "Oh wow, what a great DS title," then proceed to praise the 3DS for playing games that weren't developed for it. A DS game is a DS game. I'll acknowledge it as such.
It's like praising the Vita's Remote Play feature for playing PS2 games, when the Vita merely doubles as a controller.