I'm not sure I'm understanding you correctly, but I just purchased a "vintage" 3rd Gen iPod Classic, 2nd Gen iPod Mini and I have a 2nd Gen iPod Classic. Plugged each one in to my brand spanking new iMac. Each one was recognised by iTunes, each one had an upadte (updates were probably released years ago but the fact they're still on Apple's servers sounds contrary to your statement).
I mean you cannot update to the latest operating system for iOS and THAT means you CANNOT and I mean CANNOT get most newer software packages since most do not support iOS 3.x any longer. What good is a 1st Gen iPod Touch without software? I'm stuck with the software I got for it two years ago and using it as a music player (most videos won't play either unless they are at a specific resolution whereas newer iPods can play virtually any resolution) so its function is severely limited. Apple could at least have an App Store sort by OSX 3.x and keep older software versions that are compatible with it available (i.e. I could still get most older versions of many software packages for my PPC PowerMac because most sites keep older versions around for just that sort of thing. The same is not true of iOS devices. Once you can no longer get the latest OS version, software will start drying up very quickly.