I too feel that MA is invaluable to ALL members, even if it doesn't focus solely on your narrow area of interest in the hobby.
The magazine's physical presence has a psychological effect: With it sitting there on the coffee table or on your bench, you're more likely to pick it up and read it. Logically, more people are likely to be aware of the goings-on in the AMA. If you've got to actively surf to a website from month to month to get your AMA information, you're less likely to do it. Heck, you can't bring your computer with you when you go to "do your business" and that's where a good share of R/C magazine reading is done
I believe an analysis of the numbers was done here on RCU, and it turns out that the ACTUAL cost of the magazine is a measly $7 per member per year. This is cost to produce and mail the magazine, minus advertising revenue, then divided by the total open membership of the AMA. I'll tell you right now from experience, our club of 100 can't publish a 6-page, 6-issue newsletter for $7 per member per year. With the AMA newsletter material taking up 40+ pages in every MA issue, and spanning 12 issues per year, there is no way the AMA could publish it for less than $7 per year.
Now, nobody has investigated whether the IRS would consider a "virtual" newsletter satisfactory for fulfiling the requirements to be a not-for-profit organization. Since the laws were almost certainly written before the Internet, I highly doubt that there is a provision for online newsletters. Their definition of "publish" almost certainly involves paper.
Frankly, I think if we got rid of the glossy magazine, and with it all the advertising revenue, AMA dues would probably go up in the end. Like it or hate it, MA is probably the most effective and fiscally responsible means by which they can disseminate knowledge, and maintain status as a not-for-profit organization.