I think this comment is a bit at odds with the usual /. opinion.
WotC literally open sourced the rules of the game and released it under a sharing license for 20 years, and a vibrant ecosystem of both free and not-free content was created around that open, royalty-free ruleset.
Now they're saying "Hey, we're going to retroactively de-license that content you all have been using, and make it closed because you're making too much money and we're not making enough." This would be analagous to Linus Torvalds unlicensing his contributing to the linux kernel because he wanted a share of the money Google made from the linux kernel underlying Android and their enire cloud platform.
WotC has greatly benefitted from the Open Gaming License (OGL) and the thriving ecosystem that has built up around their d20 system. You paint this as a company wanting to benefit from their own work, but that's the stupid part: they are. The OGL is actually one of the most powerful modern corporate success stories for the benefits of copyleft licensing, and now they want to kill the golden goose.
They're free to release new content under any license they want. If they want to be stupid, and go back to a restrictive license for their new content, more (stupid) power to them. But allowing a large ecosystem to build up around their open license would be like a city charging $1 for perpetual land leases, and once a big, thriving, revenue-generating business sector develops changing their mind and saying 'Well, we didn't really mean perpetual leases...'