Maybe the experience is different on other systems, but on Fedora with KDE there already is no friction to installing random stuff. If I want to install, say, Google Chrome, which is not in the normal repositories, all I have to do is download the package and open it. A nice GUI program then takes care of the rest for me automatically; the main differences from installing a program on Windows is that it then updates automatically and I have to enter my password.

So really, there is less friction than on OS X--I don't have to drag anything anywhere! In fact, on Firefox, I just download the package and it figures out to open it with the right program automatically. And then it just works.

Of course, if a program is in the repositories it's even easier, but that's a different story...