Email is actually pretty great for this, and email is especially powerful for giving writers direct connection to their readers. But there are limits to what you can do there, and stuff like community discussion, audio and video, and even 'not accidentally going to the promotions tab' can get a big upgrade.
Somewhat related: developing for email is still a pretty big pain. It's kinda like the bad old days when you had to support IE6 - lots of people still use old versions of outlook or whatever.