As a member, I can say VA does not fly to many international destinations beyond the country list they accept as members. Pretty much just two.

And as you said they are partners with Delta and many other airlines, so you can earn points and status on those partners if you aren't able to become a Velocity member.

Velocity is a pretty good program, but I can't see why anyone would be upset they can't join if they don't live in the South Pacific.