Actual trend is suppress anything free and not fully controllable: usenet is decentralized and no one can really own it so it's pushed as much as possible to the oblivion, offering colorful and limited substitute from StackExchange to Reddit passing through HN and /., same for mail, they are not distributed but still decentralized enough to be out of complete control, so here came webmails just to avoid people keep their messages locally and paving the way to new "email substitute" that are web-only, fully centralized etc, Slack, Google wave etc are all tentative to bury emails in the past. Webcrap is the same, instead of a WWW of hypertexts. Push of mobile instead of PCs is the same.
Also with these kind of "modern" solution we as clients can't really discuss, try HN, try Disqus we do not really have control and voice, we are only data producer to be milked.