In the Kuhnian sense, Syntactic Structures was the vanguard of a paradigm shift that let linguists do "normal science" in terms of positing a range of problems and writing papers about them. It was also useful in computer science for formally defining computer languages that are close enough to natural languages that people find them usable.

On the other hand, attempts to use the Chomsky theory to develop language technology failed miserably outside of very narrow domains and in the real world Markov models and conditional random fields often outperformed when the function was "understanding", "segmentation", etc.

From an engineering standpoint, the function that tells if a production is in the grammar that is central to the theory is not so interesting for language technology, I mean, if LLMs were -centric then an LLM would go on strike if you got the spelling or grammar wrong or correct you in a schoolmarmish William Safire way but rather it is more useful for LLMs to silently correct for obvious mistakes the same way that real language users do.

The other interesting thing is the mixing of syntax and semantics. For a long time I believed the "Language Instinct" idea of Pinker in which the ability to serialize and deserialize language is a peripheral that is attached to an animal and you need the rest of the animal and even the surrounding world to have "human" competence. Now LLMs come around and manage to show a lot of linguistic competence without the rest of the animal and boy we have egg on our face, and coming out of the shadow of the Chomsky theory, structuralism will rear it's head again. (e.g. "X is structured like a language" got hung up on the unspoken truth that "language is not structured like a language")