Oh Jees... not this CRAP gain! We went through this last year, at about the same time too.
Short story = All tractor manufacturers (attention ericm979) do this... the only reason JD is being singled out is that it is the only US manufacturer, all of the rest are foreign (Head Office) based = silence/don't-give-a-d@mn.
If you want to muck around with your JD's electronics they (JD) are more than happy to sell you the diagnostic equipment/programe... just like they do to an independent mechanic. It's no different than what the car manufacturers do regarding non-OEM vehicle service companies or a local mechanic.