横から失礼します。
>情報源を教えていただけませんか?
Appleが正式に発表した見解ではありませんが,ユーザフォーラムで,よく話題になっています。iPhone copy paste gestureなどで検索すると,ヒットします。
http://forums.macrumors.com/showthread.php?t=416475
以下などが代表的な意見と思います。
Copy/Paste is *not* a small upgrade, as it entails adding a new memory layer, adding whole new gestures for selecting text, copying, pasting, and possibly cutting. As it is, some of the gestures (multi-finger scrolling in iFrames comes to mind) are already not immediately obvious, and screen real estate for new “buttons” is limited and fairly crowded.
Copy/Paste is not a priority on the iPhone, because it is not intended to be a clone of your desktop computing experience - it isn’t a natural fit for the iPhone.