[T-R]

I don't think it's a preference for dedicated devices in that instance - the electronic dictionaries are just better than most cell phones for that purpose. Most people haven't switched over to smart phones, so the screens are small, and the English alphabet doesn't map all that well to a cell phone keypad (compared to a QWERTY keyboard, or Hiragana on a cell phone keypad). Newer electronic dictionaries also have a stylus and do handwriting recognition. On the other hand, the Nintendo DS electronic dictionary is pretty good, and much cheaper than an equally functional 電子辞書.