Following up on the previous post regarding the effect of aggregation, there's also another effect on author's content. The message is ripped from its original context and inserted into another context.
For example, "previous post" above makes sense if you're seeing that post in the context of my reverse chronological posts. If you get it in a webfeed aggregator, that might not make much sense.
A relatively straightforward and oft discovered observation. But when do we hit the point where people start writing more for aggregation than for the monolithic site. Or is good writing/content inherently aggregable (sp?). I don't actually believe that but it's an avenue worth pursuing.
Somebody should get out there and do the experiment of being just a "webfeed" author and skip the weblog stuff.