Why is being boring considered a bad thing?

I'm a boring person. But I'm ok with it. I'm happy being boring. Being out-going just doesnt agree with me. But when i talk to others, the answers I get are: you're not boring. You're one of my closest friends. etc. But that's the end of it. I know I'm an ok conversationalist, and I do choose interesting reading material...but these folks dont really have anything in common with me. We dont hang out in public. But of course, most of what they want to do are more of an active thing, and I'm more passive. Also, even the movies some of my friends like are totally opposite of what I like. I know they're fun...but they dont think I'm boring? By their actions, I know they think this, but they say I'm not, so I think they think being boring is bad. Is being boring bad? If so, y?