The only reasons I can see for people disliking Lennon here are literally because he was human. Maybe he might have run out of original material if he had lived.
But he certainly had a good run whilst he was alive. Who cares about what could have been? He was, and that's all that matters.
Please stop hating each other. This is a song with a peaceful message. And I think a call for peace is quite appropriate, considering the events in Libya, Afghanistan and other Middle Eastern countries.
That isn't genetic engineering. The dictionary definition is "the direct human manipulation of an organism's genetic material in a way that does not occur under natural conditions". Farmers do not do this.
Okay, so maybe farmers do select the attributes of crops they like, for example. But they're only introducing a single layer of selection, of which there are many others in the natural world. E.g. temperature, wind, soil. But this is not genetics, it is selection and speciation.