There's lots of reasons to buy organic. First, it's better for the environment. No pesticides means healthier soil, water, and wildlife. Buying organic supports small farmers. Organic farmers can earn a fairer price for organic produce compared to factory farming. Organic farming is good for biodiversity. Organic farmers are growing a wide variety of non-genetically modified (non-GMO) fruits and vegetables. Where factory farming has shrinked our choices in the supermarket to one or two types of any produce variety, organic farmers are resurrecting many heirloom varieties.
Finally, organic foods are healthier for you. The research on whether consuming organic food is healthier for people remains inconclusive. However, the USDA's own tests show that most non-organic produce contain residual pesticides even after washing. The long term effects of consuming these pesticides has not been sufficiently studied, but they can't be good for you.