I guess the counterargument here would be that LLMs could improve research as well by optimizing menial tasks. It's kind of similar to how computing has enabled brute-force proofs in math. But I think the fact that students are still required to prove theorems on paper and that problems with brute-force solutions are still studied analytically should show that tools like computers or LLMs are not at all a replacement for the typical research process.
I've been wondering lately about how to distinguish between tools that enhance your cognitive ability, and tools that degrade it. Jobs called a computer a "bicycle for the mind," and it seems like LLMs are an easy-chair for the mind. I'm not sure a priori how to distinguish between the two classes of tools though. Maybe there is no other tool like an LLM.