Indeed, it may be desirable to render whatever is available instead of showing an "Internal Server Error" to the end-user.
However, if include Pages are missing, essential parts of web pages may be missing (resulting in a bad User Experience).
I assume you do want to log this problem in order for System Administrators to be alerted ASAP. Where should the logging be done? Model Service log file? Web Application log file? Both?
Should the rendered Page still contain the missing Regions containing an error message, similar to Entities for which model mapping failed?
Note that we're prioritizing incorporation of Community-reported Issues with associated Pull Request in DXA 2.2. So, if you want to have this included in DXA 2.2, please submit the Issue and Pull Request on GitHub.