The reason to release the 3e rules as CC is because Pathfinder 1e is still a thing, and it's sitting on a stack of cinderblocks that are the 3e SRD under the OGL. And Paizo has already decided to move on from the OGL with 2e. So that means there is no one left to make a strong stand if WotC goes after the OGL again. Lack of trust isn't just a feeling, it's a decision that has to be made by third party publishers. Trust on the OGL is just about zero. People keep publishing OGL stuff that is low risk, and nothing else.
And trust, as a choice, is not just about 5.5, it's about an entire ecosystem of publishers and writers that grew up around the OGL in the early 2000s and have been betrayed multiple times at this point. Early deployment of 3.5, which became a lot less compatible than initially promised; 4e; 5e; the OGL debacle; then 5.5, again with trying to bury earlier, legally accessible versions of their rules. So then the 5.5 SRD comes back to try to patch things up. But there are still people who are sore, who took financial damage, with 3.5 and 4.0 and 5.5, and those people need to be shown sincerity.
And although it's conventional these days to talk about "virtue signalling" as a sort of fake performative act, real virtue virtue signalling, in a sociology sense, means demonstrating an apparent sincerity of believe by paying an actual cost for the virtuous behavior. Releasing SRDs of older rules sets under the CC and other open schemes would be actual virtue signalling. It would show generosity and collegial spirit toward third party publishers, the people who helped make D&D the success it is today, and many of whom now work for WotC.
