The true reason for FMCA wanting more members is to finance FMCA Assist. They cannot afford that program with the current number of members. Here's a description quoted from their web site:
"FMCAssist Medical Emergency and Travel Assistance Program
From the first day of your membership, you’re automatically covered 24/7 by FMCA’s Medical Emergency and Travel Assistance plan, FMCAssist. It’s built into your membership, at no extra cost to you, and coverage is worldwide. In case of an accident or serious illness during your travels, you, your motorhome, your children, your grandchildren and your pets will be returned home."