While I certainly do agree with you on principle. I can sort of see a bit of the argument on the other side. Breeding a good new variety often does take some time and, usually a lot of money, and I can certainly see the breeder wanting to recoup some of what he or she spent doing it. In an ideal world, I suppose, people would voluntarily give the breeder some funds to make up for what they spent (or we'd live in some sort of socialist paradise where earning enough to survive was never something you had to concern yourself with). But in this world, few people are going to pay for something if they don't have to. And if you are a very little grower, and the person who gets your seeds is a very big one, it's pretty easy for them to out-produce you so much that you CAN'T sell any of yours because they can beat you on price due to volume. If you're little known, they could even claim THEY created it and find some way to get exclusive distribution rights so you COULDN'T sell, or even grow, your own anymore.
I suppose you could argue that every breeding project is supposed to be for the good of everyone, and so each breeder has an obligation to keep doing it AND handing out the fruits of their labors for free, that any costs they incurred doing that it was their DUTY to pay for the good of everyone else. But that sort of turns plant breeding from a labor of love, or even an attempt to better the human condition, into something like slavery.