Wow, Plunjer did you reinstall Tiger 10.4 (and upgrade to 10.4.11) or Leopard 10.5 (and upgrade to 10.5.4)?
Basically, I believe this problem cropped up way back around 10.4.9 and 10.4.10 .... I believe that Apple released an update which decreased power to the USB ports -- maybe even to specifications -- and the first thing that happened was that I had numerous clients lose the contents of their USB drives... I had a rash of all-out drive failures, color calibrators would not connect, my small cell phone would no longer charge, etc.
The newer updates fixed the all-out failures (I think) but left the underpowered devices. I now suspect Apple was trying to get a lower-powered specification, underdid it, and then brought it back to specs (maybe) but it basically killed many peoples' ability to hook up external drives without external power. I can't believe that peoples' jump-flash drives weren't connecting! Those are low-powered devices!
Eventually, I found that I could use a USB hub creatively but even that didn't always work.
Alas, I don't think Apple thinks this is a real problem... they probably took things to "specification" and are like "look, it's to spec, these other companies are at fault"... pretty ridiculous argument. People do the same thing with law, science, nutrition, etc. People just made up those specifications at some point ... it was probably a conservative decision that was part-economic, part-practical, part-safety, part-functional. And I'm SURE there are numerous other specifications that Apple does not tightly adhere to. In this case, we were better off when they didn't...