I have taught for the past 15 years in MLS programs at San Jose, Illinois, and Dominican, so my comments regarding the requirement are grounded in my experience as an MLS-holder, an LIS educator, a supervisor of MLS students, and someone who has been able to hire dozens of librarians over the years (where some positions required the ALA-accredited degree and others did not).
I have also taught for the past 4 years in the M.A. in Nonprofit Management program at DePaul University, so my comments regarding the requirement are likewise grounded in my experience of the fact that non-profit management is also a credentialed field that, like librarianship, involves a commitment to a core set of professional values as well as core competence in areas of critical concern to Association management.
My thinking about this requirement has also been shaped in recent weeks by the debate over the ongoing commitment of the Association to the core values of the profession engendered by a series of press releases issued by the Association since the November election in the U.S. In this regard, I have been thinking about the complementary roles of the Executive Director, the ALA President, and the other elected members of the ALA Executive Committee in ensuring a values-centered approach to ALA leadership (where "value" is understood as the commitment to certain shared beliefs about the role of libraries and librarians and library staff in society, and not solely in the bottom line).
With those caveats:
1) I believe that there are certain core competencies required in this position in regard to its responsibility for administrative leadership of the Association, stewarding Association resources, committing to professional development and support for the Association's staff, etc., and that these competencies are not tied to the completion of an ALA-accredited degree (which includes degrees other than the MLS, of course). These may be found in those who have completed degrees in Nonprofit Management, for example, or who have served in leadership positions in libraries, other cultural heritage organizations, other nonprofits, or other Associations
2) I believe that it is absolutely critical in today's environment that the ED be able to demonstrate his or her commitment to the core values of the LIS professions. This commitment seems to be what many assume may be assessed, by proxy, through the possession of the MLS degree, but I do not believe that assumption is wholly accurate. There are many who have shown their commitment to the values we embrace through their work, inside and outside of cultural heritage organizations, who do not hold the professional degree. And, there are those who hold the professional degree who I might question in terms of what values actually guide their decisions as librarians and as leaders.
3) I believe it is critical that the Executive Director, sharing a commitment to our values, understands how to best make use of the professional expertise represented by the elected leadership of the Association, including the President and President-Elect, of course, but expanding to other elected leaders at the Executive Board, Divisional, and Chapter levels. For many, a gap seems to have opened up between "Big ALA" and the work they are doing to advance our profession and our shared values at the local, state, and other levels. A new ED should commit to a deeper engagement with the professional leadership in shaping his or her work in administrative leadership.
4) I note that ALA is a professional association, and not a library, itself. Thus, my comments regarding educational requirements for leadership positions in a professional association should not be assumed to reflect my thinking about educational requirements for the position of library director (we can have a side discussion regarding what I think about trends in librarianship and in higher education, more broadly, regarding the recruitment of senior leaders from outside the fields represented by the organizations they have been recruited to lead)
If those commitments are the ones guiding the selection of the next Executive Director, we can craft a much more strategic and meaningful recruitment effort than one where so much is assumed through one's possession (or not) of the MLS (or other ALA-accredited degree). Rather than depend on the degree as proxy, let's search for the skills, values, and commitment to professional engagement (and respect for professional expertise) that we need. There are many excellent librarians who might fit this bill, but there are also many excellent Association professionals who are not librarians; I'd advocate allowing as many excellent candidates into the pool as we can, and then focusing on finding the one who has the best combination of core competencies, values, and commitment to collaboration.
So, the short answer for the tally: I recommend making the MLS (or ALA-accredited degree) no more than a preferred educational requirement, but I could even see an argument (in the context of a very well-written position announcement) for making it a desired requirement.