Many programs actually do, to a varying degree. Some programs are very vague but others can be specific. In the article, the virus even explains it: to install additional codecs. It might have even tricked me into thinking that it might need those (maybe they are integrated into quicktime and thus needs those privliages).

Almost any program that does something more advanced stuff then emails needs a helped application which often requires a root password. This is unfortunately true and apple is not very interested in fixing it (because their AppStore is safe and you ought to only use the AppStore because it will be sufficient for all your needs -- at least that's what the geniuses at Apple told me, which is actually good advice for most people but from time to time they need to enter the root/admin password and you can't really educate "normal users" when to enter it and when not to).