It's probably well worth questioning the value of any of this crap above and beyond whatever immediate social value it gives. I can't think of anything more ephemeral and useless than blog comments--does it really matter whether those are backed up for the ages?
It's probably worthwhile giving your users a chance to recover their content. It's probably not worthwhile to be a digital packrat.
I mentioned commenters and comments because I wanted to discuss the roles either party could play, not because I wanted to highlight their value. That said, some bloggers do have highly interesting discussions in comments, in part because they see value in them and spend some effort moderating them.
> I can't think of anything more ephemeral and useless than blog comments--does it really matter whether those are backed up for the ages?
You might be surprised. Archaeologists are forced to derive much of what they know about vanished cultures from bits of ephemera from their daily lives -- things you'd find in a midden heap, like shards of discarded pottery, spat-out plant seeds and gnawed animal bones, and the like. Why? Because those are the things that survived.
Would our understanding of those cultures be richer if we could hear their songs and read their poetry? Undoubtedly. But we can learn an awful lot about them from their ephemera, even without that.
If we're worried about archaeologists, we should inscribe our blogs on stone tablets and bury them underneath our houses. Short of that, backup tapes will decay, hard drives will fail, and if the data somehow stays alive in the "cloud" in a form that's accessible to archaeologists of the future, then they'll surely have an utter surfeit of data.
It's probably worthwhile giving your users a chance to recover their content. It's probably not worthwhile to be a digital packrat.