So the 3DS is basically a success enough but not a lot of people seem to agree that this is because of the 3D gimmick. I'm not too sure about that though, and here's why. So, first of all, media attention. The announcement of a portable system with 3D features did actually cause some extra attention to my knowledge. And guess what? There's kids out there, you know. Enough of them easily fell for that gimmick and wanted a 3DS. Believe it or not, I think these kind of children were a very determining factor for the success of the 3DS. If we compare this with the Wii U, I think the Wii U couldn't get as much sales because the tablet concept isn't exactly new to them: and it didn't wow them. Nowadays all children seem to use tablets so that makes the Wii U less special. Back when the first DS launched the concept of two screens including a touch screen was really awesome and refreshing, so the DS became popular. Back to the point. When the 2DS launched, I've seen people stating that this move was obvious and that the 3D feature of the 3DS wasn't needed. I disagree very much. Gimmicks are what can start the success of a console. There's many different types of people and thus it was a great idea to introduce the 2DS though because the people who really didn't care for the 3D can now get a 2DS and still play the games. It doesn't really matter that the 3D feature ended up being less useful than the motion controls for the Wii for example (in my opinion), because the important part is that it helped to start the sales of the 3DS.

i like the 3D effect and always have it on.

I think the main issue was that $250 price tag during launch which after they did that huge price cut in the same year lead to a loss per unit... Anytime Nintendo or any other company releases a new hardware, it gets media attention anyway but the main reason as to why the 3ds is winning so much is cause of its games that is targeted towards a broad audience as well as a consistent first party support.

I do use the 3d often during games cause I like glass free 3d. My issues with 3d movies and etc has always been the need to wear glasses and everytime I go watch a 3d movie, I just fidget around with the glasses like every 5 minutes and its soo annoying so imo, the 3d on the 3ds was a nice move but it was no way required to sell units

I think a good library of games is more or less for keeping the sales up. At launch there aren't many games and you'll have to convince people with the hardware itself. That's how I see it anyway.

I do have to wonder if Nintendo over-reacted with the price cut. Cause they basically slashed the price by $100 which might have been too rash? Maybe if they did it by $50 or no price cut at all and just bring on the games, they could have sold the console for $200-$250 but I wonder if it still would have sold 40 million units just based on the games library alone

Yeah, there's no real, true, solid evidince why those 40 million units got sold I guess. :(

It stopped the piracy

http://gamrconnect.vgchartz.com/thread.php?id=105088

Oh wow XD

I use it to take nudes of girls im dating :P

Simply no.
The 3D screen, made console more expansive, and more complicate. To have the 3DS effect Nintendo decided to sacrifice on more more important aspects, like portability, battery life, construction quality. About the 3D effect parents were indifferent in the best case, and cautious in the worst case. So no, the 3D effect was a wrong idea and the console was bombing hard before a big and unhealthy price cut and Mario Land / Kart saved it.