This is a response to Jeff's post. Sorry I'm weighing in so late.
My first thought on this is that maybe its time to ask them. I know that's sort of the point of this discussion but if they're not reading blogs…
Anyway, if I had to make an educated guess, I'd say it's a combination of time and perceived value.
1. Time – Reading anything takes time. I'll concede that finding relevant content and setting up a reader takes about 30 minutes. However, actually making time to read blogs is another story. I skim so much of what I subscribe to these days just because I don't have time to take it all in.
2. Perceived value – The blogosphere used to be filled with people writing about their cats and/or Howard Dean…some people still think it is; they would rather read a newspaper or foxnews.com. Or as Lisa Junker pointed out, focus on more important stuff:
colleagues who already put in long hours and just don't want to think
about work any more when they could be spending time with their
families or on private hobbies or what have you.
They don't know what they can get out of the deal. And those that do are confronted with too many barriers to entry – too much to think about, too many components.
IE7 didn't convert the masses as expected (not by me). I guess we'll have to keep educating people.