I do not work on NLP, but my understanding was that, for purely syntactic work, standard parse-tree-based techniques had been quite successful in NLP; and that it is only for semantic work that symbolic representations begin to show weaknesses. Since we often care about the meanings of words, this is a pretty strong limitation; still, it suggests that standard grammar-and-parse-tree approaches do capture something significant about how human languages work.
I don't work in NLP either, but from my understanding, the boundary between syntax and semantics is never as clean as one might imagine, and each language draws the boundary differently, so in general the utility of just looking at syntax can greatly vary.
Another issue is that many real life sentences have more than one possible parse, and we use context and semantics to disambiguate, e.g. how do you parse 'fruit flies like a banana'.
Is this inaccurate?