Question: why do we bother with special issues of journals for conferences?
In an effort to appear scholarly, I googled a bit and found this article ("If Special Issues of Journals Are Not So Special, Why Has Their Use Proliferated?" by Richard T. Mowday in the Journal of Management Inquiry). That article considers special issues devoted to specific research subfields, rather than conferences, so is not very relevant to my question. (Various arguments for and against are dismissed as invalid, but they don't include the ones I mention below.) The topic arises in this blog post (Lance Fortnow, "Are conferences worth fixing?") but the topic is merely touched on in some of the comments.
My general understanding is that your conference paper is supposed to acquire a seal of approval from being invited to the special issue. The other motivation is that the journal paper should appear more rapidly than usual, but this does not always happen in my experience, and the delay of having to coordinate one's paper with half a dozen others is partly to blame. So we return to the "prestige" motivation. The trouble is, that the journal hosting the special issue, is not necessarily the one you would have submitted the paper to, in the absence of a special issue. Some people decline the invitation to the special issue (and submit to a different journal), and that seems to severely undermine this purpose of a special issue.
Am I right that special issues are supposed to be prestigious? I realise that any answer is to some extent, a self-fulfilling prophesy.