I also think that I have inherited the 'hoarding' gene from my parents & grandparents. It was a thing, in their day, never to get rid of anything that might come in useful.
I totally get that, even in my younger Gen X age. As someone who has been poor her whole adult life, I have a very hard time letting useful things go. I keep thinking I could use something, or sell something for money, or barter/trade something...it's a very stressful way to live, actually. Tons of stress and worry over 'things.'
I love my books; my photography; my genealogy, etc. I want to keep all that. They are 'me'!
I agree with keeping one's hobbies. It is a source of joy.
There are projects that I have spent much time, energy and money on, and that I may use again,in future work, so I would find it annoying to get rid of all that.
This is a tough one. Annoyance aside, it is usually best to take a deep breath and let these things be passed on to others who might want them. It's also bad Feng Shui to keep the energy of unfinished projects in your life. You can never find peace if there is a niggling bother in something you keep around.
It's very hard, though. I am always dealing with learning to let such things go.
I have lots of things that belonged to the children when they were little; and also my own things from the past. Time seems to pass so quickly and when I hold their things, I can re-live the past. I find this important, because my memories of that time need help, since I was very ill after having my boys ~ depression with the one; ulcerative colitis with the other ~ and still quite unwell when my daughter was born. (I really should spend less time on here, and more time with them, while they and I are still young enough to do things together!)
These things seem to bring you peace and good memories, so they are not really clutter. If maybe you could do a little weeding from time to time, it might be a good thing. Are there other family members who might cherish some of these mementos?