Getting back to the question posted by the OP, my guess is that companies don't publish snowboard weights because then that would be another quantifiable standard that their QC would have to conform to. More testing => more cost passed on to the customer in terms of higher price. Somewhere along the line, I'm sure some marketing person figured that the costs of doing so outweighed the benefits (benefits as defined by marketing, meaning more boards sold, not meaning a lighter, higher tech, "better" board). Or maybe the marketing team figured, best leave the weight debate to bloggers/gear reviewers/forum posters, so they don't have to be accountable to what is being quantified.
I know bike companies publish weights, but probably because the cyclists who really care are willing to spend upwards of $800-$1,000+ for a bike.