It is because of our inability or refusal to accept a guiding hand that nature has come to be regarded as a system that can be engineered for our own convenience, or as a nuisance to be evaded and manipulated, and in which anything that happens can be 'fixed' by technology or human ingenuity. If a fraction of the money currently being invested in developing genetically modified crops were applied to understanding and improving traditional systems of agriculture , which have stood the all important test of time, the results would be remarkable. It is a huge oversimplification to say all farming ought to be organic or there should be no GM foods. I'm sorry, but life isn't that simple. Man has been tinkering with food production and plant development for such a long time that it's a bit cheeky to suddenly get nervous about it when, fundamentally, you are doing much the same thing.
People are worried about genetically modified organisms getting into the environment.