I’ve been meaning to write this down in one place instead of scattering it in comments throughout the Internet. Note that the following blithely ignores the question of copyrighting mechanics; I agree that mechanics can’t be copyrighted but am assuming there’s concrete value to having a license for them anyhow. I also am assuming that the ORC will have a viral component; if not, it’s almost certainly going to be strictly inferior to Creative Commons Attribution.
WotC releasing the D&D 5.1 SRD under a Creative Commons Attribution license is not just one of the better outcomes for fans, it’s a shot across Paizo’s bows and probably the only one that would have mattered. Paizo’s still going to release the ORC and Pathfinder will go under that license, but it won’t have the same effect it might have otherwise.
We’re already seeing this with the Kobold Press announcement that they’re focused on maintaining compatibility with 5e. Their material may also be released under ORC, but that’s far less important than convincing Kobold to focus on Pathfinder 2e as their primary focus.
Why does WotC’s decision matter? Because permissive licenses which do not require licensing derivative material are more attractive to corporations than viral licenses, all else being equal. In 2014, the GNU viral licenses were the most popular licenses in one study, with 45% of the market. In 2021, viral licenses only had 22% of the market. These studies probably didn’t use exactly the same methodology, but the second study has seen a several year trend of GPL popularity declining and the old Black Duck surveys also saw GPL popularity declining.
It also makes sense. If you’re not an idealist, would you rather use a license that gives you more control over your product or less? More is better from a purely capitalist standpoint. Do you want to build your third party fantasy dungeon supplement on a license that restricts what you can do in any way, or on a license that gives you complete freedom without having to worry about getting product identity declarations right? Bonus points for the fact that D&D owns the majority of the market, so you reduce some barriers to entry by basing your supplement on 5e.
There’s also an advantage to being the mechanics originator in an OGL-style licensing model, because ultimately you’re the only one who can restrict usage of new mechanics. Consider a supplement with a new class in it. If you’re WotC (for D&D) or Paizo (for Pathfinder under the likely ORC), you can publish that supplement without releasing the class as open content. Under a viral license, nobody else has that freedom.
WotC has demonstrated that they’re happy to do this. Paizo hasn’t had the opportunity to make that choice until now, since they’re using the OGL and thus have to release their mechanics. From the point of view of a licensor, it’s better to choose a license that doesn’t give a competitor more advantages, even if they aren’t using them right now.
I don’t know if anyone at WotC went through a similar thought process; it’s possible that they lucked into the smart move. Either way, it was the right move.