Now, I can certainly understand how this gets left out. You are space limited in most grant proposals, so it's certainly enticing to just jump right into what you want to do and why it's important. But, remember, to show the importance of your study, you need to offer contextual research. More than that, you must show you're the right person for the job by showing the contributions you've made to research in this area in the past.
To do this, I give you a formula for describing and contextualizing your project in the research...
Describe the cutting edge of current research:
You don't want to give reviewers a full literature review in your grant proposal; most likely that's not an option with page constraints anyway. But you do want to give them an overview of the most cutting-edge research in the field. Remember, some reviewers may not be in your exact field, so they aren't up-to-date on the latest and greatest, so let them know. Use this description of the cutting edge to generate some excitement about the field and your work.
Show your contributions:
One thing PIs sometimes forget is that they not only have to make a case for their amazing research, but they also need to show that they are the best person to do this research. So, when you're describing the cutting edge research, be sure to position yourself in it as a thought leader and cutting-edge researcher yourself.
Identify the gaps:
Once you've clued your reviewers into what's happening that's so exciting in your field and what you've done thus far, segue into what is the next thing that needs to be done. Outline the gaps in the cutting-edge research and what needs to happen to keep the field moving forward.
Sometimes PIs outline the gaps in their grant proposal but don't take the extra step to explain why it's so important to fill these gaps. This can be a fatal flaw in a proposal. Don't assume that your reviewers will inherently understand why your project is important. Close the loop and explain the whole thing, even if you think it's unnecessary. Your reviewers will be thankful for the clarity.
Show how you will fill it and offer the ongoing vision
Once you've made the case for your project, show how your project will accomplish all the needs that you described in your case. And as the icing on the cake, bring them back to the vision of your research and what will be possible in the future as you progress.
If you use these items as a checklist, you'll be sure to incorporate all the items you need in your proposal to make a clear and compelling case for your project.
Resources:
The Heilmeier Catechism
Heilmeier Catechism: Nine Questions You Must Answer to Develop a Meaningful Data Science Project - Data Scientist Insights