That is an incredibly naive viewpoint given how agribusiness behaves.
Their modified crops cross pollinate with standard strains and "become" the modified strains. Then they sue the farmers for not paying the license fees. They threaten to not supply farmers with GMO seed if they use normal seed for their other crops.
Similarly they attempt to patent strains that have existed for centuries in order to become sole providers. See the Basmati / Texmati rice case for just one example http://www.no-patents-on-seeds.org/index.php?option=com_cont...
They have made every effort to remove other options from the farmers and are creating monopolies through questionable business practices and IP abuse.
It's a dirty business all around and it's a clear indication that the patent system is broken. Commodities are cheap, because they are commodities. Simply because anyone can jump on in and have a go at producing them. That's the free market at work, cheap and lots of it.
Contrast commodities with the protected patented good. Expensive and a limited supply typically, since you can only get it from the IP owner or a licensee. Why innovate if you don't have to and if you do, make sure it's patentable and stretch it out.
If patents were fair and equitable all around then people would not be trying so hard to turn commodities back into patented goods.
It's not tenable and it is the cause of our current economic malaise. It's a high tech world and the path to economic growth is blocked because as soon as you computerize or mechanize, you run into a wall of intellectual property that you can't get around without gobs of money for lawyers.
The software startup world was the wide open frontier ten years ago, a place where you could make money with just an idea, but it's gradually getting the life choked out of it by IP law.
Sorry, I did not initially mean for this to become a patent rant, but it is connected to everything I have been thinking about for the last year or so and it's really pissing me off how far it's tentacles go.