The importance of the research proposal:
A research proposal is a document of usually three to seven pages that informs others of a proposed piece of research. This proposed research is usually a Masters or Doctorate by thesis, but it can also be work for a corporate purpose. University students usually write research proposals for academics who may eventually supervise the work based on the proposal. A research proposal can be rejected as unsuitable or poorly designed and on the basis of this, a piece of research can be rejected. The proposal is, therefore, an important document; one that is worth spending some time on to get right. Another reason to get the proposal right is that this can save you time in the long run. If the proposal is well-designed, it can form an outline of the thesis to follow, and ideally, can be mapped onto various parts of the final thesis.
source:
https://library.unimelb.edu.au/__data/assets/pdf_file/0011/1924085/Exam_Preparation.pdf