Nova remarked in comments (ahem!):

Well, the thing about IRC is that I just haven’t found anything feasible to replace it. It still remains as the most powerful means of chatting, and for myself also works as a feed aggregator thanks to some nice smart scripts. All in all modern chat clients tend to be stripped of much of IRC’s functionality to make them appear simple to use. You don’t need to care about networks and such, or type in commands. In the process the developers of these programs use the excuse of “social networking” to incorporate features that in fact limit the social usefulness of their programs – pretty much with all these IM programs, GTalk and whatnot you need to already know at least some of the people you are going to chat with. It’s like an IRC network where each channel is password-protected.

I tried GTalk and a bunch of other IM services, Facebook and whatnot. And I found that in terms of usability and function they are more obsolete than the ancient IRC protocol they’re supposed to replace.

He's right about the superiority of IRC when the problem of communication is approached as he does it. However, let me build a flawed and opaque analogy here: the Space Shuttle. STS is the largest launcher in the world, and the Shuttle can carry biggest payloads and biggest crew. It also has unique capabilities such as cargo return. And it is about to be terminated without replacement. Some people look at it like Nova at IRC; they rue the loss of function. Others point out the enormous costs. IRC costs a lot too, just like any chat: the chatter must pay constant attention to the conversation. But I have better things to do with my life. Even blogging, for example. So, IRC is the best chat, but someone might want to jettison the chat concept completely, in favour of other communication modes. Maybe even not electronically mediated ones, you know?

As for having an open entry, it's not unique to IRC. The noise and the need to admit new sources into the channel are in constant conflict. I pretty much had to go the opposite way: read a semi-stable set of anime blogs that hopefuly cover what I possibly want, do not pump too much garbage, and gradually propagate new sources. It more or less works these days, although I have to say the link density is rather unsatisfactory overall (with some bright spots).

BTW, #animeblogger is linked off the navigation section of all AB blogs. But many other channels remain somewhat or entirely secret. E.g. I know that Evirus ranges much further than #raspberryheaven and Omo rubs with Moy somewhere, but I never was able to figure it out. Evidently, many IRC users consider it as the exact opposite of the open model that Nova espoused above. For them a key-protected channel would be a feature.