Package management goes way beyond installing and uninstalling stuff. A good package manager, like apt or yum, will help your computer self-update (not only the core OS but every program you installed in your computer, through the same interface). It also shines where you don't want to know from where you download a given package - you just ask for the package manager to install it. The good package managers will also deal with dependencies and conflicts between packages, which is something that may not appear when you deal with applications but happens all the time with libraries.

You insist there is no need for package management because you never had real package management. The Macintosh method is very simple (much better than the Windows way) but it fails miserably when what you are installing is not an application.