Part of the problem is that Bungie don't allow duplicate clan names, and so many names are taken up by dead clans with 1 or 2 people still in it that haven't played in years. This means most clan names are either a clan name with random characters, or completely random because people have sat for so long trying to find something available that they end up with the "f it that'll do" option. Edit: to add a point, it's a reasonable question that you're not alone in thinking. It seems that there is often recruitment threads of people saying "Looking for a clan with a cool/funny name".

Our clan is named in honor of my dear sweet grandmother