I don't mean to echo Thereisnospoon303, but he raises good point. When you say "childish, livejournal-esque topics", what exactly do you mean by this? What topics make you angry?
I really am curious to see your reactions to many of the replies in this thread. My experience here at this forum has been the complete opposite of yours. In my experience, the level of discussion here is, on average, considerably better than any other MLP community that I have seen. There are some discussions here that are very serious and in depth. Perhaps you should seek them out before you draw conclusions about the entire fandom?
Look, I admit that maybe some topics here on this forum may seem silly or immature to you. So what? Why does it upset you that some people just want to have fun and clown around a bit?
Look, this is an online community. There is nothing that is childish, immature, or stupid about people posting here looking for sympathy, support, or praise. As a matter of fact, the posting of such topics is a good sign of a healthy community - a community where every member feels welcome no matter what their age or background is.
Age is just a number. Someone's age is, at best, only a rough determinant of their nature. Someone of a very young age can have more wisdom, knowledge, and life experience than someone that is far older. Some of the most amazing people that I have ever met have been teenagers that have accomplished great things in life. Are you aware that the creator and maintainer of this forum is a teenager?
Really, I don't think that your problem is age. I think that your problem is something else. I say this respectfully, but I think that you need to smile, relax, and not take life as seriously as it seems that you are taking. Life can be serious enough without being so concerned about "childish" things.
You wrote earlier in this thread that you realize you're getting old when you no longer enjoy the simple things in life - like the snow. I'm older than you by a few years, and I still enjoy the snow, the rain, the sky, etc. Actually, I have had some very harrowing experiences and seen some very sad things in my life that lead to me enjoying these things all the more.
In the overall scheme of things, a human life lasts for only a very short duration. You should make the most of it. Don't allow getting a little older to rob you of the glimmer of light in your eyes.
I leave you with this quote.
"Critics who treat adult as a term of approval, instead of as a merely descriptive term, cannot be adult themselves. To be concerned about being grown up, to admire the grown up because it is grown up, to blush at the suspicion of being childish; these things are the marks of childhood and adolescence. And in childhood and adolescence they are, in moderation, healthy symptoms. Young things ought to want to grow. But to carry on into middle life or even into early manhood this concern about being adult is a mark of really arrested development. When I was ten, I read fairy tales in secret and would have been ashamed if I had been found doing so. Now that I am fifty I read them openly. When I became a man I put away childish things, including the fear of childishness and the desire to be very grown up."
- C.S. Lewis, "On Three Ways of Writing for Children" (1952)