The membership change isn't about building the reported membership count. It's about being clear that USFAA works for all alumni, not just those who pay into it. As someone who has run one of the USFAA chapters, I've seen first-hand that engagement is hurt by the perception that you need to be a dues-paying member to take part in any official USFAA activities. In reality, we were hosting activities for all alumni and friends of USF regardless of their membership status.
This no-fee membership is the model the most alumni associations are moving towards and has been a trend over the last decade or so.