I'm often curious why I don't see some of the people with somewhat high rep in chat. True, chat's not for everyone, but is it a matter of them not being aware of it to begin with, or a conscious decision to ignore it?
I'm sure that I don't qualify as having a high rep, but here are a few reasons why I don't stay in chat:
I don't know what it's good for. This explains nothing:
The Bridge of Gaming's StackExchange™ AlienOverlord AskQuestion™ mothership, wherein we charge our lazers in search of Super Waaaana Bro.
It's too temporal. If there's no one around at that exact moment to answer whatever question I have, then I'm better off asking at the the real site, or on meta.
It's confusing. I have to guess at where a conversation might have started by by scrolling way up.
Chat gives the appearance of requiring a higher level of commitment.
When at work, there's no harm in browsing through a few questions / tossing out an answer. But joining a chat room might be regarded as being actively unproductive. This is the difference between reading a blog entry and signing onto personal MSN Messenger - the latter being more dangerous to daily productivity.
When at home, there are games to be played, and other recreational things to be done. Again, the issue is one of commitment - either you're chatting, or you're doing something else.
The chat puts itself in a bit of a catch-22 position. To be effective, people have to join and talk with each other... but people aren't likely to join and talk with each other when there's nothing going on in the chat.
I am a high rep user that generally avoids the chat; not out of any dislike for it per say, but simply because I don't see a use for it. Why join the chat when I could just ask a question on the site instead? (The recent exception to this was about a week ago when I joined to ask something I knew I couldn't ask on the site: mod recommendations for Oblivion. I left without any real answers.)
I don't think this is limited to gaming's chat (and honestly, based on my experience with stack overflow's chat rooms, gaming's is generally more active!), but right now, there's simply not enough reason to hang out in chat unless you want to mingle with strangers over the internet.