There is one big advantage of Usenet and e-mail over a forum: the raw data is parsed by the user's client and this can be processed by the user in any way they want.

You cannot do this with WWW (this very much helped the commercialization of the Internet btw). 'Web 2.0', JavaScript, CSS, XML, RSS, extensions attempt to make life easier by giving back some power to the user; but the core issue is still there. This conflicts with HIGs and such, and before you know it you have all kind of themes and websites optimized for all kind of devices. Or clients which pull the data via HTTP://, abstract it, and then put it in an optimized UI again.

OTOH because some metadata is saved server side (what have you read last time you logged in) some settings are saved for any logged in client. In e-mail this is the case as well, but not with Usenet.

IRC is an entirely different beast because it is real-time interaction and meant as such.

I believe e-mail and Usenet are good ways to communicate provided they are useful on the device we serve (including, preferably, backwards compatibility) with easy howtos to get these working well 1) effeciently 2) aesthetically on the device. Then, all the users are on an abstract platform while the power users can draw the power from their client and make everything the way they want it to be.