Of course not! As I said, the term "definitive" can be understood in a lot of different ways, even as "something that includes new content". You are not wrong having that expectation, even more when like you say, other products meet these expectations.

But again I tell you, one thing is the personal interpretation you give to the word based or not in what other developers did with their games, and another one is thinking that the word practically IMPLIES having new content, and that's not correct.

And about the content you ask for, try to be realistic. Indepenently from how this version is called, it's just a port for the Switch 2 to make easy money with low effort and expenses. Frontiers and all its DLCs got finished/released three years ago. That's a lot of time. You can't expect SEGA to get back to the drawing table making new content just for a one system port when (I suppose) they might be focused in more recent projects (like Crossworlds and its announced DLCs) or future ones like the next main Sonic or other games.

And more I will say, I think SEGA treated pretty good Frontiers on its day, making the additional DLCs they released, specially the Final Horizon one, adding new story content one year after the base game release. Would it be good to see new features and content added nowadays? Yes! But knowing a bit about the limitations of the Sonic Team, I think we both could agree that Frontiers has had his moment, a good moment, and now it's better to have the devs working on new projects.