The problem with patented seeds (and everything else) is the owner can decide who gets to use them. No one should hold that power.

If patents worked as a royalty system where you're guaranteed to get a license if you pay there would be no problem. But right now Bayer can use their control over Roundup Ready plants to make farmers buy more products they don't need, or punish them for dealing with competitors, because they have a monopoly.

And it also lets them set the price to anything they want because competing with them is illegal. Exclusive rights are always like that.