About fast Medical Request matter these days, I think it is happening because the whole process time reduced to below one year in CIC's time frame.
As we know Medical result is valid for one year and when we look back to CIC's processing time, we can see they reduced application's processing time from 2 years in 2012 & 2013 to about 10 months these days. Because most of the cases are going to be finalized in about 6 to 8 months after EP AOR then it is better for CIO to ask for medical request just after sending EP AOR to have a complete application with medical result in it and reduce further delays.
In the past years when processing time was about 2 years, CIC tried to send medical request in the last stage of its waiting and processing time and always the next stage of medical request was passport request in those days but today the whole process is about 10 to 12 months, First 4 months application is waiting in CIO and next 6 to 8 months it will be processed in local visa office. When they ask for medical request in the 5th month then they are sure, applicant will get visa when medical is still valid and it will not expire for at least 4 months after visa.