I am a PhD student (mid stage) and my work includes the use of mathematics. I try to learn as much as possible. I am facing a problem: I spent enough time on the mathematics required for my research, and according to my research supervisor I am good at understanding proofs, theorems, etc. at an intuitive level, but in writing I still have some work to do. Many times I try to write things and, although I think I am not that so bad, there is still a problem to be resolved.
Question: Is writing in research so very important? I have seen some research papers of some star people whose writing does seems to be very impressive to me (although I may be wrong).
Edit: Please note that I don't consider myself a star: that's why I am asking this question. I am trying my best to improve my writing skills and it has improved to some extent, but to me it appears that I may not get that much better at writing. Let me tell you a story: once during my PhD I worked with a professor other than my supervisor, and then we got some result so he ask me to write a paper. I took 4-5 days write a paper 8-9 pages long, then he told me that I wrote in a cryptic manner. (This happened in my first year.)