So, there are plenty of ways to view the data in a sheet, and to regulate access. My issue is when a sheet contains sensitive data, and that you want to give view and update access to only a few of the columns via a report. A good example is a column for internal comments and one for external/customer comments. Since an external user has to have access to the main sheet in order to work through a report, that user can, at any time, go to the sheet and look at all the data that is not available through the report.
What I would like to do is to not share a master sheet at all, but give access to a report only. In that report, I could set access rights to the master sheet that would override the rights of the user to that sheet. This user could then update the columns he has been given access to by using the report, yet never be able to go to the master sheet to even view the data.
This is an official request, and hope that it will be considered for a future functionality.