I see both sides of this discussion.
Second, opposition to JDs side. The problem that arises when access to the technology is needed. To give the owner complete access to the technology for repair purposes opens the door to their data secrets. To give the owner the ability to reset codes for example also gives the owner the ability to be deceptive in warranty debates. For example, engine overheated because of no cooling system maintenance. Machine repeatedly coded. Owner got access to the JD Link and deleted all of the codes. Then claimed it never notified him. Or,,, owner wants/needs a bit more HP. Access to JDs system allows him to "tweak" the fuel system to gain that power. After all, he's the owner and should be able to do that. Fine and dandy until something goes wrong.
There are things about the technology that is aggravating. But the gain far outweighs those things.