For desktop use, sudo let's you elevate your permissions as necessary (polkit kinda replaces some sudo stuff, but similar concept). The reason you want this is when you run anything, it will _by default_ run as your unprivileged user, not root. That is a huge security benefit and pretty standard across desktop OS these days.
Now on a server, sudo for a single user probably doesn't make sense, just use root and keep it simple.
