mIRC is generally not a private chat system even though you can chat in private. It is more for chatting with many others in a channel (aka room). As such, you'll find many people who prefer not to receive private messages without reason. Not all channels are going to be active because anyone can create a channel and there aren't any rules requiring that the channel is active. And all channels can have their own rules or anything else they want. If you want a channel to just chat with people, try looking for channels with chat in the name.
As far as a feature to do what you want, that's probably not very likely to be added. First, the nature of IRC would mean that only a relatively small number of people would actually take time to use that. As it is, most people don't even use /away when they aren't at their computer. So adding yet another command or feature to show other kinds of statuses isn't likely to have any better interest among most users. What you're looking for would be of interest to a small number of users who have a similar interest. As such, it would work better as a script that they all use. But getting a lot of people to use a particular script isn't easy unless it really offers a lot of benefit or is required for a channel that those users want to be in.
Your best bet is simply to find a good channel that has people who have similar interests and just chat with them there.
