According to proponents of the open source method, this is good because the bugs are caught quickly, and anyone who can read C can understand and create extension to the system. Most of the applications and utilities are distributed under the GNU GPL , which means that they are also open. Those who are daunted at the prospect of learning countless arcane commands have a choice. The GUI doesn't completely insulate the user, though. A certain amount of CLI is always helpful when using Linux.
Most tasks are faster and easier from the command line anyway.
As for the arcane commands, not to worry. Most full distributions come with a set of electronic documentation. New software comes with its own documentation. Speaking of software, Linux supports almost every type of software anyone might want. From programming to word-processing, from games to web development, we have it all.