I do agree with DIY being a way to move beyond the "made to fail" philosophy! I get incredibly frustrated with commercial products that are "made to fail" or made with no possible hope of being repaired. Like most of you, my basement if full of old stuff because, while these items may not work, they contain lots "useful parts." Cue my wife rolling here eyes at me...
Having said that, DIY still requires a bit of planning and forethought for ease of maintenance in the future. I really wish I had taken this into account when I built my first set of DIY amps about a decade and a half ago. I've recently run into a problem that requires some poking around, isolating, and testing various points and I'm discovering that there are LOTS of design choices that I should have made that would have greatly simplified future maintenance. I'm probably still no where near as good at this as I need to be, but I am getting better at it.