I sincerely appreciate folks recognizing my work and keeping my name attached to things derived from it. I am fortunate enough to still be working full-time in the hobby market and Wizards has derived a surprising amount of new material from my fiction and TTRPG contributions, so those credits matter a lot. Crediting past creators in a shared world is also simply the right thing to do. That's true whether the creative folks are still working in the hobby or not.
Posts on social media can have an effect in our hobby. When Shadow of the Dragon Queen came out and it turned out the designers and editors had left my name off the inspirations list, even though they'd included Caradoc and some other things I'd created as prominent parts of the work, it was a fan posting something about the absence that ended up prompting a discussion between me and Wizards. That chat resulted in them apologizing to me and promptly adding the inspiration credit in for the ebook and for future printings of the physical book, should it go back to print.
But that comment was framed like the comment above about the Van Richten's team, noting the missed opportunity. (I would have loved to see those names listed, too; one of the joys of working on a shared world for me is being included on credits with talented younger and more diverse designers like the new VR team, being part of the same continuity and shared design pool. These inspirational credits lists are hard to construct and balance out sometimes, though; at least they called out the VR team as a team.)
All that said, Wizards, the folks working on the new book, and the actual play team did not steal my work or my ideas or the characters any more than TSR stole the character of Soth from Margaret and Tracy when they decided to move him to Ravenloft. They own the material. They can do with it as they please, beyond violating any contracts for the works--and those do not talk much about credits. (The contracts should, and I hope the push to unionize parts of the tabletop market will result in working conditions and contracts that improve long-term credits for folks. The model contracts we are working on at the Tabletop Game Designers Association will include some clauses about creator control of their own name, as well.)
Ideally, people working in a shared world and the companies or individuals that own those worlds will credit the creators who built the IP they continue to explore and even get those foundational designers involved when possible. They should at least treat the source material with respect. In this case, the new team both credited their inspirations and, from all I have seen, certainly treated the material with overt respect. I might have been happy to participate had they asked, but there are corporate, budgeting, and scheduling reasons that might made that impossible. But they checked the credits and respect for the material boxes. All good by me.
I mentioned corporate intentionally there. At a corporate/IP ownership level, there are forces that want to erase creators or at least minimize their importance in shared worlds. Make them interchangeable. Erase past contributions. Brand over individuals. I've been on the publisher side of things and have seen those forces at work. Social media posts and chatter that frame legit uses of shared world material as theft or the like empower those forces. The next time an opportunity arises to slap a house name like "Richard Awlinson" on an important project rather than listing the human creators, or to use company-owned AI, they will trot out high-profile negative or misdirected or false posts from or about authors and credits as justification. Posts framing these uses as theft are also simply, factually wrong.
So if your intention is to draw attention to creators or to get the powers that be to do better by them, take a more positive tack. There are times when hurling the rhetorical brick can become necessary. Over the years I've thrown a lot of them myself in public comments about publisher treatment of creators, and many more in private with the publishers themselves. But pick the projectiles and the reasons for hurling them a lot more carefully. Unless you are just hoping to smash stuff up and start fights, you can do actual unintended damage to the chances for creators to get better treatment from publishers by recklessly hurled false accusations.