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Most of the projects you name are major projects with considerable communities and vested interests. If they also go some way back, it stands to reason that mail was their primary communication system and that has stuck. This has grown out of the academic world, but when something like 95% of all email volume has become spam, and you have to take draconian measures to keep it working, something has gone wrong. And that's just a detail; my real beef is with the (non-)organisation of email.
I recognise your description of the developer/user split between mailing lists and forums. The strange this is that for me, it's the other way around. The last time I preferred email was when I had it in Lotus Notes, and I was running my own Notes server to synchronise it over all my machines and work places. I had to let go of that when I migrated to Syllable and Linux, which lost me all that convenience. Since then, I can only simulate some of the same convenience by going with the web and cloud trend.
There's a reason that I like Syllable and other simplifying technologies. It must have something to do with the reason that regular users prefer web forums. It's distinctly different from the old academic mindset that produced email and Linux. It has always been my mission to offer regular people systems made with a different mindset: more convenient and much more integrated. As you can see, I need network technology for that, so clients and servers, and that's why we added Syllable Server and REBOL to the Syllable lineup. All of them are important pieces of the puzzle.
Regarding AltME: it's indeed what they call a darknet these days. But it's not a darknet because you can't get in, but because people don't bother to visit. So here's the situation: people always claimed operating systems sucked and they wanted better ones, we spent a decade of our lifes creating it for them, but people simply refuse to even have a look at the collaboration system that we chose to produce Syllable. It embodies the Syllable philosophy of integration and convenience: it's not a loose collection of email, IRC, FTP, CVS and what not, but a holistic, efficient, cross-platform groupware system with a nice graphical interface. We're not going to degrade our own productivity by dumping it for the sake of lurkers who demand but don't contribute. This street goes two ways. Nevertheless, as I said, we desire to open it up more, and eventually even replace it with our own system, but we're working on that gradually. Syllable Server was the first step.