The GoodReads criteria (if they have any) strike me as terribly arbitrary. I have 500 reviews on their site, 900+ on Amazon, and a personal review blog, and I've won... 2 giveaways. Out of entering hundreds.
With NetGalley, they seem to have an unlimited number of licenses to give out. With GoodReads, there's usually not even a dozen copies. And a lot of them seem like "vendor trash", by which I mean ARCs well after the book has already been released. Now, I don't mind getting an ARC one tiny bit, BUT it does start to seem like they're using GoodReads as a recycling program.
Bottom line, I wouldn't take the rejection personally -- I think it's fairly random.