The main difference between keeping usefull stuff and being a hoarder is if its organized. When you move one thing and a stack falls over or you find broken and smashed things buried under others its gone too far.
Of you can keep it onganized to where stuff isn't getting lost of broken and its not a danger to you or your family or the person rescueing you then its still ok
I ended up building a second shelf in the top of my closet so I can double stack things. We are buying a bunch of those closetmaid cubicales because they are nice ~12" cubes that come in different colors so you can sit them on a shelf and they look nice. One holds all the blank cd/dvd media and cases and labels, those may only get used a couple times a year but are handy to burn a bunch of pictures on for the grandparents, or about once a year I'll burn each family members important documents and they go in the binder in the safe as another method of backup.
Another one has my set of electronics books, another a set of books for c programing, either I might not use now but may in the future as the kids get older.
But they are organized and don't fall on you, if you were to say go to my inlaws house and walk into a bedroom there is a big desk with stacks of stuff and if you try to blow the dust off the top a pile will tumble down.