It doesn't help, I think, that this is a sore spot with DH and I about HIS stuff. (HIs thing is usually, "I might need it someday." He isn't sentimental. It's about...what if?)
I'm guilty of this, too, and I'd totally let go of it except that there have been too many times where I'd been right. Besides, there's something hormonally rewarding about cannibalizing otherwise worthless junk, repurposing other things, and solving a complex problem for free. Improvise, adapt, overcome.... oooh rahhh!
But yeah, every once in a while, it is necessary to look through that junk again, because clearly some of those things that get saved end up obsolete. I'm pretty sure I won't need those extra phone cords anymore... but then again, they'd do as a pretty strong rope in a pinch...