@jjmusa2004 had a similar viewpoint on cloning. Personally I see it's potential for replacement parts for people but am against it for creating new life just as you are.
As for agriculture, you are correct that sometimes the machines can increase productivity but at a cost. Pollution and reliance on fertilizers and fuel. I'm hoping that science can look past the industrial model of agriculture and help us with small scale, sustainable agriculture (here's looking at the science of Permaculture).
As for playing God with people and nature. I'm pretty much opposed to that. People haven't proven themselves to be responsible with ultimate power. I'm hoping humanity becomes more mature before science moves too far.....but I think that is wishful thinking :)
i don't want to imagine 'ultimate' power in the hands of men or a few 'privileged
The rich already have near ultimate power. Giving that little extra doesn't appeal to me either.