I think the problem is societal in nature.

As problems in society increase, people have less time for "self help" and spend more time just making ends meet.

Also, men are much less likely to seek any help for any problems, both professionally and in a "self help" format. 

I think that general attendance at alanon meetings has declined in general, that has been my observation, with many local meetings actually closing due to non attendance. 

Perhaps men have come to the meetings, seen that there are few men, and then did not want to come.  They may have felt they were not well understood by the women and did not have the patience to wait to see if other men would come.

I have found that men and women alanoners are very different, since by nature, men and women are so different.  Despite any marriage or family problems, most men must continue to work and so have more opportunity to develop social support networks than many women do, who may be trapped at home with young children while married to an alcoholic.

Most men, since they continue to stay employed the majority of the time, are not "trapped" in alcoholic marriage, and have many more options to leave the unhealthy environment.  Men have the tendency to live more in the moment, and are not classically very good at self reflection, once they leave the alcoholic relationship, fewer men than women would see the need for continual "support" in alanon. Women feel trapped much more often, and so seek comfort and support in alanon in their uhappy family arrangement.

Alanon originally was designed for women in a time when divorce was not socially acceptable, it helped them learn to cope with being stuck in a marriage to an alcoholic when they had few options, if any.  I think that even though Alanon invites all, its philosophy is based in general on the needs of women.  For example, "shares", most women feel very comfortable talking about feelings openly, most men don't. 

Personally, I can say that I have beneffited IMMENSELY from the men I have known in the program.  I had never before heard men speak so eloquantly and fully about their feelings, it was very eye opening. 

This post is simply sharing my personal observations based on my background in sociology and psychology.  I am not an expert, and don't purport to be, so take what you like and leave the rest .