Jmcculley, Great question! It has to do with the physics of how the strings vibrate on the instrument. The best sound is produced from a precise length of the string. It is so much harder to tune with just the violin pegs though, so I still recommend keeping the fine tuners, they just make life easier! They make tailpieces now with special fine tuners to try to accommodate this problem and provide as much length as possible while still using the fine tuners.
Suzanne with Violin Tutor Pro