@briankrebs
The nontrivial factor which I know you're aware of but should really be mentioned, is link rot.

Sure, it's not a problem....right now. But in 5 years, if that company goes under and another one moves in, even with 3 years time warning ahead, some random person finds an old document via a search engine that talks about this URL. If it's a .gov address, no prob, 301. But what if it's a domain you just...don't control anymore?