First off...all fruit contain seeds naturally. The purpose of the fruit is it to hold seeds and hopefully be consumed, digested and excreted to a new location. This germination symbiotic relationship happens in all areas of nature. Most commonly with bees and flowers. Seedless fruit is genetically modified fruit and has no place in nature.
The modifications are secret and patented by big named corporations. At first people assumed the fruit was for convenience. Who wants to be seen spitting out the seeds of an orange or watermelon in public right? That tiny vanity made a niche market for companies to make a mutant fruit that has no seeds. It also took away the ability of the consumer to grow their own fruit. Say you brought a delicious bag of apples and decided you would grow some for yourself. With seedless fruit its not possible.
Seedless fruit takes away the ability to be self-sustaining. It makes you the consumer more dependent on the grocery stores for survival. When I was a kid almost all my aunts and neighbors had gardens where they would grow fruits and herbs. Everyone knew how to grow their own food and went to the grocery store only for necessities. Now most people use the grocery store for their only means of sustenance.
I'm not saying to stop eating seedless fruit, although if you eat natural its definitely more healthy. The only way to get naturally grown fruits these days is from local markets. If you buy it from a grocery store, it costs almost triple the price of the gen-mod foods... so it can be expensive. What I am saying, is for a fruit to be seedless it has to be genetically engineered. Its sterile, infertile and the lasting effects from its consumption are still being debated by scientists. So if you are what you eat, and you're eating sterile and infertile food...what will happen to you?