At a Nintendo meeting today, honcho Satoru Iwata (above, blowing crap up) replied that if there were too many 3DS models, consumers would be become "perplexed" (or even, "bewildered") by all the choices, and thus, they could get lost in deciding which 3DS to get.
Nintendo, I'll make it simple: Release a 3DS with an extra circle pad on board, and we'll all buy that. See? Simple! Phew.
Continuing, Iwata added that the new model, the 3DS XL, was created to fulfill "the need" for a larger screen.
"The need" for an extra circle pad will be handled by the release of a Circle Pad Pro for the XL, which is a larger version of the Circle Pad Pro for the current 3DS and which is totally not confusing.
任天堂 第72期定時株主総会の様子（質疑応答中心） [現実ゲーム]