A couple years ago WotC decided to attend a much larger number of events, including a lot of things--like Comic Con in SD and NY, and the Wizard World shows--where they might attract new people to the hobby of gaming. To make that happen, they had to cut resources from the core hobby shows they supported. At the end of the day, they decided that Origins was redundant in its proximity to Gen Con, and it was one of the cuts.
I'm not aware of any falling out with GAMA, or any mustache twirling, or anything like that. Simply a case of deciding to put resources elsewhere for more benefit. One may or may not agree with that decision, but either way there really wasn't more to it than that.