It's annoying, but if stardock lets it out early, it'll undurcut the retailers, and they'll get pissy, and they won't be able to find any foreign distributors. And that's generally regarded as really bad.
Aren't the retailers already getting it way later due to ship time? IIRC the release date is not the date it'll be in stores, only given to those who ordered digitally, so it won't be on shelves.