The charter of the NGA, and the mission that we are dedicated to continuing, is to educate and encourage gardening in the US.
There is a vast difference in the gardening challenges right here in the US- it is difficult enough to run a website, operate a podcast, and run a database for *US* specific information- vastly different from coast to coast. We are not prepared to be able to educate and encourage world-wide. That's simply not feasible.
It's not about inclusion/exclusion. It is about practicality. One organization simply cannot be familiar with world-wide growing conditions/pests/diseases. Very different from dealing with other world-wide organizations who aren't working to help people grow things
That said, our community is certainly worldwide- it always has been, and there's no reason why it won't continue to be so.