[EdiX]

Because orchestral music is high brow. The melody in orchestral music, for cultural, acoustic and agility reasons, is usually written in the soprano range, and therefore it is given either to violins or woodwinds in that range.

Unlike woodwinds, a violin doesn't drip on the floor: if you are playing an instrument for social status not having a puddle of spit (or a damp cloth) at your feet is important.