Oh I've been playing this one armed bandit long enough to know the truth!The one and only reason why you should interact with a forum is if you enjoy the interaction it self. If you need a point system to motivate you to do so than you are in it for the points and not for the interaction. And that is called a Skinner box design and is a very unhealthy thing. It's basically chasing a point high. And you should not be doing that.
In fact, if at any point in any interaction be it a forum or an online game or anything else you catch your self doing it not because you enjoy the experience but because it makes you earn points LEAVE immediately.