Re: It was also HARDWARE that no longer exists.
I think it also helps to understand how government-owned equipment is tracked and handled.
In a public agency, when you buy something, it goes on the books at the value you paid for it. Unlike in private industry, it does not depreciate. You have to account for that thing, at full value, until it's eventually auctioned off.
This makes retaining disused equipment a real pain in the butt, because someone's going to have to go physically find it and inventory it every time there's an audit -- otherwise you'll have headlines about how your agency "lost $1.2 million in equipment paid for by taxpayer dollars" even though that equipment was worth more like $1200 by that time. Or someone will come along and ask why you're renting all that space that no one's actually using (another big budget criticism of government agencies.)
If you keep archiving stuff, eventually your budget becomes dominated by that, and you can no longer do your agency's original mission. The best outcome is to donate it to a museum for archiving, but museums aren't always interested, especially if the equipment is bulky or is mostly just obsolete commodity hardware.
Stuff in storage becomes a real bureaucratic headache and the incentive is to dispose of it, which is usually a good thing. Space is limited, after all. Often ground station equipment is removed to make room for a new mission. Remember, this satellite was dead as a doornail last time they checked. It's not like they pulled the plug on Voyager or something.
That's not to say NASA couldn't do a better job with archiving important data from landmark programs -- I once met a guy who had the data tapes from Viking I in his basement, for crying out loud. But I don't think this particular mission is an example of that. You have to prioritize.