Dear taylor_31,
In addition to the dispersion of seeds caused by consumption of edible fruits, many fruits when falling to the ground provide a ready niche of decomposing material for the new seedling to be nourished from.
Also, if you research most edible fruits and veggies, you will find that often they did not taste very good intially, but have been hybridized for years to produce the big, sweet fruits we see today. There are many fruits which do not taste good: crabapples, wild rose hips, wild strawberries and mulberries, etc. in this area, which are still providing the same function for the plant.