I was afraid I was going to find this as “the official answer”. I see absolutely no reason to restrict what data can be reported. If your customer says it is relevant, then you should help them collect (and manage) that relevant data. Sometimes, like with screenshots of what is on there screen when the error occurred, are vital to tracking down the cause of the bug.
So, as a quick fix, PLEASE work on integrations with Google Drive, Dropbox, and/or S3 compliant file storage services to send binary files and have links/integration in sentry’s reporting UI.