Today has been a distracted, fractured sort of day at work. And so, you get my random thought of the day. The words "needed" and "necessary" mean almost the same thing in the right context. "He decided that doing so was not needed." "He decided that doing so was not necessary." At least in English contracted braille, though, it is less effort to write the much longer word. "Necessary" is three letters, while "needed" is two letters and two contraction symbols. The longer word is shorter.