A new console can't compete with a console 5 years into its life cycle. That's a ridiculous comparison to make. Try comparing 3DS to '05 or '06 DS instead.
The problem that comparision is that the DS was a new brand surrounded by considerable confusion, because the GBA was still in its prime when Nintendo suddenly just released the DS and a lot of people early on didn't know if this was some kind of experiment on Nintendo's part (a lot of people felt the DS was a stop gap for the "real" Game Boy Next back in those early days).
So the DS had an extremely slow start. The 3DS shouldn't have that excuse though, it's the successor to the second best selling platform in game history, the formula and brand momenteum should be there for it.
Much like the Playstation 1 to PS2 -- the PS1 had a sloooow start, but it had to build its brand those first couple of years. The PS2 rocketed out of the gate because it didn't have to.
The 3DS already has had a monstrous price cut, it was Mario 3D Land, it has Mario Kart 7, Kid Icarus Uprising, it has Resident Evil (x2), MGS, Tales, it has Mario Tennis, Zelda: OoT, available in many different colors, etc. Sales should not be this sluggish. Honestly from a game library POV, the 3DS is considerably stronger IMO than the DS was at this point.