Matt and Larry:
I won't argue that both MUM and TLR are not excellent publications; I completely agree that they are both superb, and the observation that many (perhaps even most)(?) people join the SAM or IBM, today, specifically in order to receive them makes some sense to me. I confess my previous comments were largely based upon experiences in the "old days" (I'm dating myself), when my arguments were more demonstrably true.
Ironically, my likeness was featured on the cover of the last issue of The Linking Ring to be published in the old "saddle-stitched" [staple bound] format, thus marking the end of a 73 year tradition (some might argue that I broke it.)
When Phil Willmarth got the go-ahead from the then IBM leadership committee to permit Tony Dunn to update the publication's look (some wannabe named David Copperfield appeared on the first perfect bound, full-color issue cover, immediately following mine), the publication instantly gained more credibility in the eyes of the reader, and as a result immediately became a more tenable advertising medium.
I speak from experience when it comes to ad response in the older-style member publications versus the (then) more "slick" paid subscription magazines. Having placed ads in both kinds, I received a remarkably higher number of "interested" prospects (but not always paying customers) with the latter kind of publications.
Though it doesn't now and has not historically accepted advertising, when I began my brief tenure as editor of The Psychic Entertainers Association's official journal, Vibrations, I made a concerted effort to change it's overall visual style (it has always been of great value to members), making it more modern, and for lack of a better term, "dynamic" appearing. I still have the letter I received from PEA founder Tony Raven (the late Bob Lynn, himself a gifted graphic designer), complimenting my efforts, and stating that it made the book look more like a "real" magazine.
Eye-appeal, then, is clearly very important, but content still reigns as the deciding measure of publication quality, in my personal estimation. The relatively recent visual style change of organizational magic publications probably did provide greater impetus to create better advertising response, and likely played a big part in the publications' success. I'm guessing (but only that), that an increase in ad revenue and more response to ads placed in these more up-to-date publications can be shown.
As Richard mentioned, the readership (recipients) of all major magic publications has waned in relatively recent times. This is no doubt a reflection of the economic stresses faced by some who have only a marginal interest in magic, and perhaps in some part to the always cyclical nature interest in the art (or craft, if you prefer) historically.
I do believe advertising (once again, what I suppose was at least part of the reason for the question regarding reader numbers initiating this topic) in member-sponsored organizational magazines and the "free-standing" publications like Genii, has become a much more level playing field, but I'll still wager that the latter media get a nudge, if a slight one, over the member issues in terms of demonstrated advertising interest and response.
This is, for me a very interesting topic, and I appreciate the comments of all who've taken part.