It was a significant action by the AAS to do this. See the above posts about Cambridge University Press curtailing its line targeted to amateurs and then consider what it would have meant for the RAS to buy it. I mean that: RAS, not BAA. If you have a Ph.D. in astronomy and you teach at a university, you cannot (necssarily) be a voting member of the AAS: you can be an educational affiliate. (I am an amateur affiliate. I edit for the History of Astronomy Division. I cannot vote or propose a session topic or deliver a paper or even have a poster at a convention without sponsorship by a voting member.) The AAS is for professional researchers. So, their purchase first of Sky & Telescope and now of Willmann-Bell signals deep commitment to new directions.
I serve on an AAS committee for professional-amateur engagement. The committee was approved three years ago, given a chair eighteen months ago, and formed this past January. Nothing happens quickly at the AAS. So, this action to acquire Willmann-Bell was highly significant. They are to be congratulated for taking the action as it is in service to the amateur community.