Letting the installer autonomously adjust the recovery partition may open up vulnerabilities where malicious software can be placed in recovery. I don’t know how accurate that is, but it makes sense to me, and would be why they want it done on a case by case basis as needed and not just a mass fix to all installs whether they need it or not.
There is one dude with a Windows 8 laptop that turns it on once per month just to take this survey.