Ah, I get to alter conditions under which I buy stuff based on my
need, this is great! It is what I always wanted! Problem is... When
I sell stuff under certain conditions I'd like my conditions to be honored. Like when I sell you a wafer stepper to make computer chips, I like you not to copy my patented technologies so that I can never reach return on investment. Even if you bought the machine and you own it now. And most costumers promise not to do so and honor their promise.
In the tractor case, I'd feel more honest (and much better in general) if I would just buy a tractor of a different brand with less stringent conditions attached. Why would you reward a tractor company that sells you stuff under screwy conditions?
First you vote with your wallet and make a screwy company rich, then you complain. Perhaps you should think before you buy something. Or, get a group of people together and make a nice case to the manufacturer. Where do we end if we can just break any agreement we make based on need?
The honest way to get to hackable tractors is to not buy un-hackable tractors. I'm all for hackable tractors, I'm all for hackable everything! So lets buy products that are hackable!