I actually don't think it's an oversight at all. Apple prefers that programs be self-contained packages, and thus easily uninstalled by dragging to the trash. Windows Uninstaller is horrid, it often doesn't list all of the programs I have installed, and can't remove all of the associated files anyways. I much prefer Apple's approach.
When I delete programs I almost always keep the associated preference files that are associated, that way if I ever decide I want the program again, I can reinstall and have all of my old preferences back again, without reconfiguring. They only take up a couple KB of space, so it's no big deal.