For a community of practice, the temptation is always towards the serious. That's serious discussions, serious content, and serious events.
This puts the community into the work (groan!) mental bucket. It's something extra we have to do. It's hard to succeed when people categorise your community into that mental bucket.
Your community joins a long list of tasks…usually at the bottom of the list. It's after e-mail, facebook, writing reports/documents, and every other possible thing someone can do before they get to working on your community.
Far better if the community was fun – or at least began as a fun community. Fun isn't difficult. It doesn't mean cat pictures, neither. It means members sharing fun stories, complaining about things, talking about their frustrations, and speaking to each other the same way they do during a social gathering.
This is a difficult sell for most organizations. However, having discussions asking whose going to the next meetup have far more value than the most technical discussions. They get people visiting because it's a fun thing to do.
People don't think of Reddit as work do they? 4Chan and Mumsnet either. In fact, these communities have become respites from work. That's a powerful thing.