If the government were to allow PR to claim citizenship under the old and new rules by date of when PR landed, before or after deadline, That would have been a little costly. Two sets of qualifications. Two online residence calculators. Two of everything. But it doesn't remove the problem of the first set of rules, subjective basic residence requirements.
I agree with the premise that those who land under the old rules apply under a difference set of rules from those who landed under the new rules. Those who landed under the old rules must still follow all the new rules with the exception of 1460 days requirement. They can still apply when they meet the 1095 days out of 3 years.
I do agree that days prior to PR days should not count towards citizenship, after all they were here TEMPORARY in Canada. The day a PR lands is the first day, first step toward citizenship, not before. Still keep the “intend to reside” (reduce dropping off application on way to airport) and must have filed income tax (filing taxes does not equate to paying taxes).
I think what I suggest is a more fair approach. Give those who landed under the old rules a chance to apply at 1095 days instead of 1460 days.