I think it was a case of "Are you with us or with the other F1 teams? Us? Ok, you're in!"
I firmly believe this is what happened.
The FIA wanted small budget teams working under a cap with everyone running Cosworth engines. So they signed up 3 small budget teams, under the promise of a budget cap, who agreed to run Cosworth engines. Political choices for an F1 that never materialised.
I think its telling that the only new team that looks to be moving forward is the one that wasn't in the original selection (Caterham).