I know people in Final Fantasy XIV who always, always wind up changing their main job to one of the new jobs from the expansion. Every single time. It doesn’t matter what role the new job has; when the next expansion arrives, they’ll be leveling up before starting in on the story content. There are also people I know who have had the same main job since the relaunch, and while they often dabble in the new jobs, it’s very much a case of “I started as Warrior, and I’m sticking with Warrior, gosh-darn it.”
Most people are somewhere in the middle. As patches and expansions change options, people will tweak decisions and builds. You might stay a Frost Death Knight in World of Warcraft but go back and forth between dual-wielding and two-handed over time as mechanics shift, or maybe you shift between Frost and Blood depending on the expansion. So how often do you change builds for your characters in MMOs?