Any change like that would have to be done by the Crown and would be out of the hands of the military. There certainly would be a lot fewer CD's handed out to PRES. Without any prior service, CIC Officers would require 175 years in uniform to qualify.Because "back in the day" no one even considered making a part-time job a pensionable endeavour. That these volunteer days may need to be counted as earned towards something, anything other than a CD was just "out there".
On a related note I recall reading a Briefing Note that had been sent to my boss when I worked in HR-Mil proposing that a wholesale change to the calculation of CD eligibility should be done for Reservists based on "a day is a day", meaning a Reservist would have to accumulate 4380 real days of service before being eligible for a CD. This was during the days when they were still trying to figure out how to determine pension eligibility for Reservists and how to calculate Class A Reserve service.