Lots of people used to do it, and encourage others to do it, before we just got this new software where everyone can now see what each user recommends. I think people are embarassed to do it now. Maybe someone should ask that guy that writes an ethics question-and-answer column for the New York Times Sunday magazine? Then you'd have an outsider's fatwa to follow (unless he's secretly a member) :-)

I myself have done it in the past on some posts, but am not always that interested in getting on the Recommended List, it depends on the post and topic. Sometimes I think it better if it's not, because it gets you a bigger audience of a different kind that you might not want, depending upon topic. Sometimes you might want it. "Most popular" sometimes means you're getting useless inflammatory feedback that you feel obligated to acknowledge, for instance.

If they ever get the user Comments lists to update properly, when used together with new tracking function available in "Following" feature, I think that getting on the "Recommended" list will grow less useful for many people, especially if they are coming here to communicate with others as opposed to those trying to gain a big audience for their opinions.