The 2DS is for kids because kids under 6-7 shouldn't be using the 3D for eye/brain development issues or something.
Yes you can turn the 3D off with a switch on the 3DS but an unmonitored kid may try it anyway and leave it on, unbeknownst to the parent unless they're over their shoulder the whole time.
It's not about being cheaper, it's about being for kids. It's lacking a few other features but for a reason; and the low price (Which will get lower within a year or two) will be enough to sell millions alone. Just watch.
If it saves me money, I might buy this instead of the 3DS for Pokemon X/Y. Especially if I can get one used. :p
