Other than the saddle being the small little piece of hardwood at the bottom of the violin that the tail gut sits on to prevent the table (top) of the instrument from getting damaged, it has an adjustable sonic function as well.
If the height of the nut is low then the angle of the string to the tailpiece will be greater which translates to greater pressure on the table resulting in a brighter tone.
In the case of instruments that have too much pressure on the table a higher saddle will regulate for dampened sound. This is often a last measure to be visited after having worked through all the other sound altering regulations.
Note. A tightly fitted saddle on the sides is not wise and can be seen on many instruments where cracks develop on either side of it. These cracks can travel all the way up the instrument along the grain which can cause a sound post crack, if on the treble side, or a crack close to the bass bar on the bass side. The reason for these cracks is because of seasonal changes (wet and dry) causing the two different woods to expand and contract.
For a seemingly insignificant piece of wood, it has its place when looking at, sonic effects and potential damage.